| Thursday, February 22 |
| Future Astro Russ Johnson is born in Baton Rouge, LA. |
| Friday, March 9 |
| Future Astro C.J. Nitkowski is born in Suffern, NY. |
| Sunday, March 18 |
| Future Astro Raul Chavez is born in Valencia, Venezuela. |
| Thursday, April 5 |
| » Major-league debuts: Gene Locklear (Reds) |
| Friday, April 6 |
| » Defeated Braves (0-1), 2-1 | Atlanta-Fulton County Stadium (1-0) | 1-0 | |
| » Starters: Dave Roberts vs Gary Gentry | First | -- |
| » Major-league debuts: Jim Crawford (Astros) |
| Sunday, April 8 |
| » Defeated Braves (0-2), 10-3 | Atlanta-Fulton County Stadium (2-0) | 2-0 | Won 2 |
| » Starters: Ken Forsch vs Pat Dobson | First | -- |
| » Lost to Braves (1-2), 4-3 | Atlanta-Fulton County Stadium (2-1) | 2-1 | |
| » Starters: Don Wilson vs Ron Reed | First | -- |
| Monday, April 9 |
| » Defeated Dodgers (1-3), 4-1 | Astrodome (1-0) | 3-1 | |
| » Starters: Claude Osteen vs Jerry Reuss | First | -- |
| Tuesday, April 10 |
| » Defeated Dodgers (1-4), 4-3 | Astrodome (2-0) | 4-1 | Won 2 |
| » Starters: Al Downing vs Dave Roberts | First | -- |
| Wednesday, April 11 |
| » Lost to Giants (5-1), 5-4 | Candlestick Park (0-1) | 4-2 | |
| » Starters: Tom Griffin vs Jim Willoughby | Second | 1 out |
| Thursday, April 12 |
| » Lost to Giants (6-1), 9-3 | Candlestick Park (0-2) | 4-3 | Lost 2 |
| » Starters: Ken Forsch vs Tom Bradley | Third | 2 out |
| Friday, April 13 |
| » Lost to Padres (3-5), 5-4 | San Diego/Jack Murphy Stadium (0-1) | 4-4 | Lost 3 |
| » Starters: Don Wilson vs Steve Arlin | Third | 3 out |
| Saturday, April 14 |
| » Defeated Padres (3-6), 8-5 | San Diego/Jack Murphy Stadium (1-1) | 5-4 | |
| » Starters: Jerry Reuss vs Mike Caldwell | Third | 2 out |
| Sunday, April 15 |
| » Lost to Padres (4-6), 5-1 | San Diego/Jack Murphy Stadium (1-2) | 5-5 | |
| » Starters: Dave Roberts vs Mike Corkins | Third | 2½ out |
| » Lost to Padres (5-6), 4-0 | San Diego/Jack Murphy Stadium (1-3) | 5-6 | Lost 2 |
| » Starters: Tom Griffin vs Bill Greif | Third | 2½ out |
| Monday, April 16 |
| » Lost to Dodgers (5-6), 2-1 | Dodger Stadium (0-1) | 5-7 | Lost 3 |
| » Starters: Ken Forsch vs Don Sutton | Fourth | 3½ out |
| Tuesday, April 17 |
| » Lost to Dodgers (6-6), 7-2 | Dodger Stadium (0-2) | 5-8 | Lost 4 |
| » Starters: Don Wilson vs Andy Messersmith | Fourth | 4½ out |
| Wednesday, April 18 |
| » Defeated Dodgers (6-7), 7-2 | Dodger Stadium (1-2) | 6-8 | |
| » Starters: Jerry Reuss vs Tommy John | Fourth | 4 out |
| Friday, April 20 |
| » Defeated Padres (6-9), 6-2 | Astrodome (3-0) | 7-8 | Won 2 |
| » Starters: Mike Corkins vs Ken Forsch | Third | 4½ out |
| Saturday, April 21 |
| » Defeated Padres (6-10), 4-0 | Astrodome (4-0) | 8-8 | Won 3 |
| » Starters: Clay Kirby vs Don Wilson | Third | 3½ out |
| Sunday, April 22 |
| » Defeated Padres (6-11), 4-3 | Astrodome (5-0) | 9-8 | Won 4 |
| » Starters: Fred Norman vs Jerry Reuss | Third | 3½ out |
| Monday, April 23 |
| » Defeated Padres (6-12), 2-0 | Astrodome (6-0) | 10-8 | Won 5 |
| » Starters: Bill Greif vs Dave Roberts | Third | 3 out |
| Tuesday, April 24 |
| » Defeated Mets (8-7), 4-2 | Astrodome (7-0) | 11-8 | Won 6 |
| » Starters: Jon Matlack vs Ken Forsch | Third | 3 out |
| Wednesday, April 25 |
| » Lost to Mets (9-7), 5-2 | Astrodome (7-1) | 11-9 | |
| » Starters: Jerry Koosman vs Don Wilson | Third | 4 out |
| Thursday, April 26 |
| » Lost to Mets (10-7), 2-1 | Astrodome (7-2) | 11-10 | Lost 2 |
| » Starters: Jim McAndrew vs Jerry Reuss | Third | 5 out |
| Friday, April 27 |
| » Defeated Expos (7-9), 6-5 | Astrodome (8-2) | 12-10 | |
| » Starters: Ernie McAnally vs Dave Roberts | Third | 5 out |
| Saturday, April 28 |
| » Defeated Expos (7-10), 5-3 | Astrodome (9-2) | 13-10 | Won 2 |
| » Starters: Steve Renko vs Ken Forsch | Third | 5 out |
| Sunday, April 29 |
| » Defeated Expos (7-11), 4-3 | Astrodome (10-2) | 14-10 | Won 3 |
| » Starters: Mike Torrez vs Don Wilson | Third | 4 out |
| Tuesday, May 1 |
| » Defeated Phillies (9-10), 3-0 | Veteran's Stadium (1-0) | 15-10 | Won 4 |
| » Starters: Jerry Reuss vs Steve Carlton | Third | 4 out |
| Wednesday, May 2 |
| » Defeated Phillies (9-11), 9-4 | Veteran's Stadium (2-0) | 16-10 | Won 5 |
| » Starters: Dave Roberts vs Jim Lonborg | Third | 3 out |
| Friday, May 4 |
| » Defeated Mets (12-11), 9-5 | Shea Stadium (1-0) | 17-10 | Won 6 |
| » Starters: Ken Forsch vs Jerry Koosman | Second | 2½ out |
| Saturday, May 5 |
| » Defeated Mets (12-12), 9-2 | Shea Stadium (2-0) | 18-10 | Won 7 |
| » Starters: Don Wilson vs Jim McAndrew | Second | 1½ out |
| Sunday, May 6 |
| » Defeated Mets (12-13), 14-8 | Shea Stadium (3-0) | 19-10 | Won 8 |
| » Starters: Jerry Reuss vs Harry Parker | Second | 2 out |
| Monday, May 7 |
| » Defeated Expos (11-13), 6-0 | Parc Jarry (1-0) | 20-10 | Won 9 |
| » Starters: Dave Roberts vs Ernie McAnally | Second | 1½ out |
| Tuesday, May 8 |
| » Lost to Expos (12-13), 4-3 | Parc Jarry (1-1) | 20-11 | |
| » Starters: Ken Forsch vs Steve Renko | Second | 2½ out |
| Friday, May 11 |
| » Defeated Reds (18-12), 5-1 | Astrodome (11-2) | 21-11 | |
| » Starters: Roger Nelson vs Don Wilson | Second | 1½ out |
| Saturday, May 12 |
| » Defeated Reds (18-13), 7-1 | Astrodome (12-2) | 22-11 | Won 2 |
| » Starters: Ross Grimsley vs Jerry Reuss | Second | 1½ out |
| Sunday, May 13 |
| » Lost to Reds (19-13), 2-0 | Astrodome (12-3) | 22-12 | |
| » Starters: Jack Billingham vs Ken Forsch | Second | 1½ out |
| Monday, May 14 |
| » Lost to Braves (13-19), 7-1 | Astrodome (12-4) | 22-13 | Lost 2 |
| » Starters: Carl Morton vs Tom Griffin | Second | 1½ out |
| Tuesday, May 15 |
| » Lost to Braves (14-19), 4-1 | Astrodome (12-5) | 22-14 | Lost 3 |
| » Starters: Phil Niekro vs Don Wilson | Second | 2½ out |
| Wednesday, May 16 |
| » Lost to Braves (15-19), 5-2 | Astrodome (12-6) | 22-15 | Lost 4 |
| » Starters: Gary Gentry vs Jerry Reuss | Second | 2½ out |
| Thursday, May 17 |
| » Defeated Braves (15-20), 2-1 | Astrodome (13-6) | 23-15 | |
| » Starters: Pat Dobson vs Ken Forsch | Second | 2 out |
| Friday, May 18 |
| » Defeated Giants (26-15), 3-1 | Astrodome (14-6) | 24-15 | Won 2 |
| » Starters: Jim Willoughby vs Dave Roberts | Second | 1 out |
| Saturday, May 19 |
| » Defeated Giants (26-16), 2-1 | Astrodome (15-6) | 25-15 | Won 3 |
| » Starters: Jim Barr vs Don Wilson | First | -- |
| Sunday, May 20 |
| » Defeated Giants (26-17), 8-7 | Astrodome (16-6) | 26-15 | Won 4 |
| » Starters: Tom Bradley vs Jerry Reuss | First | -- |
| Monday, May 21 |
| » Lost to Giants (27-17), 9-4 | Astrodome (16-7) | 26-16 | |
| » Starters: Ron Bryant vs Ken Forsch | First | -- |
| Tuesday, May 22 |
| » Lost to Reds (24-16), 6-4 | Riverfront Stadium (0-1) | 26-17 | Lost 2 |
| » Starters: Dave Roberts vs Clay Carroll | Second | 1 out |
| Wednesday, May 23 |
| » Lost to Reds (25-16), 4-3 | Riverfront Stadium (0-2) | 26-18 | Lost 3 |
| » Starters: Don Wilson vs Jack Billingham | Third | 1½ out |
| Friday, May 25 |
| » Defeated Pirates (16-20), 7-2 | Three Rivers Stadium (1-0) | 27-18 | |
| » Starters: Jerry Reuss vs Bob Moose | First | -- |
| Saturday, May 26 |
| » Lost to Pirates (17-20), 7-2 | Three Rivers Stadium (1-1) | 27-19 | |
| » Starters: Ken Forsch vs Nelson Briles | Second | 1 out |
| Sunday, May 27 |
| » Defeated Pirates (17-21), 6-2 | Three Rivers Stadium (2-1) | 28-19 | |
| » Starters: Dave Roberts vs Steve Blass | Second | 1 out |
| Monday, May 28 |
| » Lost to Pirates (18-21), 4-2 | Three Rivers Stadium (2-2) | 28-20 | |
| » Starters: Don Wilson vs Dock Ellis | Third | 2 out |
| Tuesday, May 29 |
| » Lost to Cubs (29-18), 7-1 | Wrigley Field (0-1) | 28-21 | Lost 2 |
| » Starters: Jerry Reuss vs Rick Reuschel | Third | 2 out |
| Future Astro Trever Miller is born in Louisville, KY. |
| Wednesday, May 30 |
| » Defeated Cubs (29-19), 4-1 | Wrigley Field (1-1) | 29-21 | |
| » Starters: Ken Forsch vs Milt Pappas | Third | 2 out |
| Thursday, May 31 |
| » Lost to Cubs (30-19), 16-8 | Wrigley Field (1-2) | 29-22 | |
| » Starters: Dave Roberts vs Fergie Jenkins | Third | 2½ out |
| Friday, June 1 |
| » Lost to Cardinals (20-25), 4-2 | Busch Stadium II (0-1) | 29-23 | Lost 2 |
| » Starters: Jerry Reuss vs Reggie Cleveland | Third | 3½ out |
| Saturday, June 2 |
| » Lost to Cardinals (21-25), 6-2 | Busch Stadium II (0-2) | 29-24 | Lost 3 |
| » Starters: Larry Dierker vs Rick Wise | Third | 4½ out |
| Sunday, June 3 |
| » Lost to Cardinals (22-25), 2-1 | Busch Stadium II (0-3) | 29-25 | Lost 4 |
| » Starters: Ken Forsch vs Scipio Spinks | Fourth | 5½ out |
| Monday, June 4 |
| » Defeated Phillies (19-31), 7-0 | Astrodome (17-7) | 30-25 | |
| » Starters: Larry Christenson vs Dave Roberts | Fourth | 5½ out |
| Tuesday, June 5 |
| » Lost to Phillies (20-31), 4-0 | Astrodome (17-8) | 30-26 | |
| » Starters: Wayne Twitchell vs Jerry Reuss | Fourth | 6½ out |
| Wednesday, June 6 |
| » Defeated Phillies (20-32), 4-3 | Astrodome (18-8) | 31-26 | |
| » Starters: Dick Ruthven vs Larry Dierker | Fourth | 6½ out |
| Friday, June 8 |
| » Defeated Pirates (23-26), 4-3 | Astrodome (19-8) | 32-26 | Won 2 |
| » Starters: Dock Ellis vs Ken Forsch | Fourth | 5½ out |
| Saturday, June 9 |
| » Lost to Pirates (24-26), 4-1 | Astrodome (19-9) | 32-27 | |
| » Starters: Bob Moose vs Don Wilson | Fourth | 5½ out |
| Sunday, June 10 |
| » Defeated Pirates (24-27), 7-1 | Astrodome (20-9) | 33-27 | |
| » Starters: Nelson Briles vs Jerry Reuss | Fourth | 4½ out |
| Monday, June 11 |
| » Major-league debuts: Tom Dettore (Pirates) |
| Tuesday, June 12 |
| » Lost to Cubs (36-23), 3-0 | Astrodome (20-10) | 33-28 | |
| » Starters: Rick Reuschel vs Ken Forsch | Third | 5 out |
| Wednesday, June 13 |
| » Defeated Cubs (36-24), 6-1 | Astrodome (21-10) | 34-28 | |
| » Starters: Milt Pappas vs Don Wilson | Third | 4 out |
| Thursday, June 14 |
| » Lost to Cubs (37-24), 5-4 | Astrodome (21-11) | 34-29 | |
| » Starters: Fergie Jenkins vs Jerry Reuss | Third | 4½ out |
| Friday, June 15 |
| » Defeated Cardinals (28-30), 3-2 | Astrodome (22-11) | 35-29 | |
| » Starters: Alan Foster vs Dave Roberts | Third | 4½ out |
| Saturday, June 16 |
| » Lost to Cardinals (29-30), 5-3 | Astrodome (22-12) | 35-30 | |
| » Starters: Bob Gibson vs Ken Forsch | Third | 4½ out |
| Sunday, June 17 |
| » Defeated Cardinals (29-31), 7-3 | Astrodome (23-12) | 36-30 | |
| » Starters: Reggie Cleveland vs Don Wilson | Third | 4 out |
| Tuesday, June 19 |
| » Defeated Padres (20-46), 7-3 | San Diego/Jack Murphy Stadium (2-3) | 37-30 | Won 2 |
| » Starters: Jerry Reuss vs Clay Kirby | Third | 4½ out |
| » Major-league debuts: Dave Winfield (Padres) |
| Wednesday, June 20 |
| » Lost to Padres (21-46), 6-2 | San Diego/Jack Murphy Stadium (2-4) | 37-31 | |
| » Starters: Dave Roberts vs Steve Arlin | Fourth | 5½ out |
| Thursday, June 21 |
| » Defeated Padres (21-47), 12-2 | San Diego/Jack Murphy Stadium (3-4) | 38-31 | |
| » Starters: Ken Forsch vs Bill Greif | Third | 5½ out |
| Friday, June 22 |
| » Lost to Giants (42-29), 5-1 | Candlestick Park (0-3) | 38-32 | |
| » Starters: Don Wilson vs Jim Barr | Third | 6½ out |
| Saturday, June 23 |
| » Defeated Giants (42-30), 6-3 | Candlestick Park (1-3) | 39-32 | |
| » Starters: Jerry Reuss vs Ron Bryant | Third | 6 out |
| Sunday, June 24 |
| » Defeated Giants (42-31), 7-6 | Candlestick Park (2-3) | 40-32 | Won 2 |
| » Starters: Dave Roberts vs Charlie Williams | Third | 5½ out |
| » Defeated Giants (42-32), 8-3 | Candlestick Park (3-3) | 41-32 | Won 3 |
| » Starters: J.R. Richard vs Don Carrithers | Third | 5½ out |
| Monday, June 25 |
| » Defeated Reds (37-34), 13-2 | Astrodome (24-12) | 42-32 | Won 4 |
| » Starters: Jack Billingham vs Ken Forsch | Second | 5½ out |
| Tuesday, June 26 |
| » Lost to Reds (38-34), 5-1 | Astrodome (24-13) | 42-33 | |
| » Starters: Ross Grimsley vs Don Wilson | Second | 6½ out |
| Wednesday, June 27 |
| » Defeated Reds (38-35), 10-2 | Astrodome (25-13) | 43-33 | |
| » Starters: Fred Norman vs Jerry Reuss | Second | 6 out |
| Thursday, June 28 |
| » Lost to Giants (44-33), 2-1 | Astrodome (25-14) | 43-34 | |
| » Starters: Jim Barr vs Dave Roberts | Third | 6½ out |
| Friday, June 29 |
| » Lost to Giants (45-33), 14-3 | Astrodome (25-15) | 43-35 | Lost 2 |
| » Starters: Charlie Williams vs J.R. Richard | Third | 7½ out |
| Saturday, June 30 |
| » Lost to Padres (25-52), 3-0 | Astrodome (25-16) | 43-36 | Lost 3 |
| » Starters: Steve Arlin vs Ken Forsch | Third | 8½ out |
| Sunday, July 1 |
| » Defeated Padres (25-53), 6-4 | Astrodome (26-16) | 44-36 | |
| » Starters: Bill Greif vs Don Wilson | Third | 7 out |
| Monday, July 2 |
| » Lost to Padres (26-53), 8-5 | Astrodome (26-17) | 44-37 | |
| » Starters: Clay Kirby vs Jerry Reuss | Third | 7 out |
| Tuesday, July 3 |
| » Lost to Braves (35-47), 1-0 | Atlanta-Fulton County Stadium (2-2) | 44-38 | Lost 2 |
| » Starters: Dave Roberts vs Carl Morton | Fourth | 7 out |
| Wednesday, July 4 |
| » Defeated Braves (35-48), 11-4 | Atlanta-Fulton County Stadium (3-2) | 45-38 | |
| » Starters: J.R. Richard vs Ron Reed | Third | 5½ out |
| » Defeated Braves (35-49), 12-8 | Atlanta-Fulton County Stadium (4-2) | 46-38 | Won 2 |
| » Starters: Ken Forsch vs Phil Niekro | Third | 5½ out |
| Thursday, July 5 |
| » Lost to Braves (36-49), 7-4 | Atlanta-Fulton County Stadium (4-3) | 46-39 | |
| » Starters: Don Wilson vs Roric Harrison | Third | 5½ out |
| Friday, July 6 |
| » Lost to Expos (38-40), 12-8 | Parc Jarry (1-2) | 46-40 | Lost 2 |
| » Starters: Jerry Reuss vs John Strohmayer | Fourth | 7 out |
| » Lost to Expos (39-40), 14-6 | Parc Jarry (1-3) | 46-41 | Lost 3 |
| » Starters: Tom Griffin vs Mike Torrez | Fourth | 7 out |
| » Major-league debuts: Otis Thornton (Astros) |
| Saturday, July 7 |
| » Lost to Expos (40-40), 6-1 | Parc Jarry (1-4) | 46-42 | Lost 4 |
| » Starters: Dave Roberts vs Steve Renko | Fourth | 8 out |
| Sunday, July 8 |
| » Defeated Expos (40-41), 9-7 | Parc Jarry (2-4) | 47-42 | |
| » Starters: Ken Forsch vs Ernie McAnally | Fourth | 8 out |
| Monday, July 9 |
| » Lost to Mets (35-46), 2-1 | Shea Stadium (3-1) | 47-43 | |
| » Starters: Don Wilson vs Tom Seaver | Fourth | 8½ out |
| Tuesday, July 10 |
| » Lost to Mets (36-46), 1-0 | Shea Stadium (3-2) | 47-44 | Lost 2 |
| » Starters: Jerry Reuss vs Jon Matlack | Fourth | 8½ out |
| Wednesday, July 11 |
| » Defeated Mets (36-47), 7-1 | Shea Stadium (4-2) | 48-44 | |
| » Starters: Dave Roberts vs Jerry Koosman | Fourth | 8½ out |
| Thursday, July 12 |
| » Defeated Phillies (39-48), 7-6 | Veteran's Stadium (3-0) | 49-44 | Won 2 |
| » Starters: Ken Forsch vs Jim Lonborg | Fourth | 8½ out |
| Friday, July 13 |
| » Lost to Phillies (40-48), 5-3 | Veteran's Stadium (3-1) | 49-45 | |
| » Starters: Don Wilson vs Wayne Twitchell | Fourth | 9½ out |
| Saturday, July 14 |
| » Lost to Phillies (41-48), 7-0 | Veteran's Stadium (3-2) | 49-46 | Lost 2 |
| » Starters: Jerry Reuss vs Steve Carlton | Fourth | 10½ out |
| Sunday, July 15 |
| » Defeated Phillies (41-49), 2-0 | Veteran's Stadium (4-2) | 50-46 | |
| » Starters: Dave Roberts vs Dick Ruthven | Fourth | 10½ out |
| Monday, July 16 |
| » Defeated Expos (42-47), 6-5 | Astrodome (27-17) | 51-46 | Won 2 |
| » Starters: Steve Renko vs Ken Forsch | Fourth | 10½ out |
| Tuesday, July 17 |
| » Lost to Expos (43-47), 7-2 | Astrodome (27-18) | 51-47 | |
| » Starters: Ernie McAnally vs Don Wilson | Fourth | 11½ out |
| Wednesday, July 18 |
| » Lost to Expos (44-47), 3-2 | Astrodome (27-19) | 51-48 | Lost 2 |
| » Starters: Steve Rogers vs Jerry Reuss | Fourth | 11½ out |
| » Major-league debuts: Steve Rogers (Expos) |
| Friday, July 20 |
| » Defeated Mets (40-51), 6-2 | Astrodome (28-19) | 52-48 | |
| » Starters: Jon Matlack vs Dave Roberts | Fourth | 12 out |
| Saturday, July 21 |
| » Lost to Mets (41-51), 5-3 | Astrodome (28-20) | 52-49 | |
| » Starters: Jerry Koosman vs Ken Forsch | Fourth | 12 out |
| Sunday, July 22 |
| » Lost to Mets (42-51), 3-2 | Astrodome (28-21) | 52-50 | Lost 2 |
| » Starters: Tom Seaver vs Jerry Reuss | Fourth | 12 out |
| Thursday, July 26 |
| » Lost to Dodgers (64-37), 3-1 | Dodger Stadium (1-3) | 52-51 | Lost 3 |
| » Starters: Dave Roberts vs Tommy John | Third | 13 out |
| Friday, July 27 |
| » Defeated Dodgers (64-38), 5-2 | Dodger Stadium (2-3) | 53-51 | |
| » Starters: J.R. Richard vs Al Downing | Fourth | 12 out |
| Saturday, July 28 |
| » Lost to Braves (47-59), 3-1 | Astrodome (28-22) | 53-52 | |
| » Starters: Roric Harrison vs Don Wilson | Fourth | 12 out |
| Sunday, July 29 |
| » Defeated Braves (47-60), 8-5 | Astrodome (29-22) | 54-52 | |
| » Starters: Phil Niekro vs Jerry Reuss | Fourth | 12 out |
| Monday, July 30 |
| » Lost to Braves (48-60), 7-3 | Astrodome (29-23) | 54-53 | |
| » Starters: Ron Schueler vs Larry Dierker | Fourth | 13 out |
| Tuesday, July 31 |
| » Defeated Dodgers (66-40), 3-2 | Astrodome (30-23) | 55-53 | |
| » Starters: Tommy John vs Dave Roberts | Fourth | 12 out |
| Wednesday, August 1 |
| » Defeated Dodgers (66-41), 5-0 | Astrodome (31-23) | 56-53 | Won 2 |
| » Starters: Al Downing vs J.R. Richard | Fourth | 11 out |
| Thursday, August 2 |
| » Lost to Dodgers (67-41), 4-2 | Astrodome (31-24) | 56-54 | |
| » Starters: Don Sutton vs Jerry Reuss | Fourth | 12 out |
| Friday, August 3 |
| » Defeated Reds (64-46), 1-0 | Riverfront Stadium (1-2) | 57-54 | |
| » Starters: Don Wilson vs Gary Nolan | Fourth | 12½ out |
| » Lost to Reds (65-46), 11-5 | Riverfront Stadium (1-3) | 57-55 | |
| » Starters: Ken Forsch vs Roger Nelson | Fourth | 12½ out |
| Saturday, August 4 |
| » Lost to Reds (66-46), 7-6 | Riverfront Stadium (1-4) | 57-56 | Lost 2 |
| » Starters: Dave Roberts vs Fred Norman | Fourth | 12½ out |
| Sunday, August 5 |
| » Lost to Reds (67-46), 7-1 | Riverfront Stadium (1-5) | 57-57 | Lost 3 |
| » Starters: J.R. Richard vs Ross Grimsley | Fourth | 13½ out |
| Monday, August 6 |
| » Defeated Reds (67-47), 5-4 | Riverfront Stadium (2-5) | 58-57 | |
| » Starters: Jerry Reuss vs Jack Billingham | Fourth | 13½ out |
| Tuesday, August 7 |
| » Defeated Pirates (54-56), 2-0 | Three Rivers Stadium (3-2) | 59-57 | Won 2 |
| » Starters: Don Wilson vs Nelson Briles | Fourth | 13½ out |
| Wednesday, August 8 |
| » Lost to Pirates (55-56), 4-3 | Three Rivers Stadium (3-3) | 59-58 | |
| » Starters: Dave Roberts vs Jim Rooker | Fourth | 13½ out |
| Friday, August 10 |
| » Defeated Cubs (56-59), 6-4 | Wrigley Field (2-2) | 60-58 | |
| » Starters: J.R. Richard vs Burt Hooton | Fourth | 13 out |
| Saturday, August 11 |
| » Defeated Cubs (56-60), 6-4 | Wrigley Field (3-2) | 61-58 | Won 2 |
| » Starters: Jerry Reuss vs Rick Reuschel | Fourth | 12 out |
| Sunday, August 12 |
| » Defeated Cubs (56-61), 3-2 | Wrigley Field (4-2) | 62-58 | Won 3 |
| » Starters: Don Wilson vs Bill Bonham | Fourth | 12 out |
| Monday, August 13 |
| » Defeated Cardinals (61-58), 4-0 | Busch Stadium II (1-3) | 63-58 | Won 4 |
| » Starters: Dave Roberts vs Mike Nagy | Fourth | 12 out |
| Tuesday, August 14 |
| » Lost to Cardinals (62-58), 9-5 | Busch Stadium II (1-4) | 63-59 | |
| » Starters: J.R. Richard vs Alan Foster | Fourth | 13 out |
| Wednesday, August 15 |
| » Defeated Cardinals (62-59), 3-0 | Busch Stadium II (2-4) | 64-59 | |
| » Starters: Jerry Reuss vs Rick Wise | Fourth | 13 out |
| Friday, August 17 |
| » Lost to Phillies (56-65), 8-3 | Astrodome (31-25) | 64-60 | |
| » Starters: Steve Carlton vs Don Wilson | Fourth | 13 out |
| Saturday, August 18 |
| » Defeated Phillies (56-66), 3-2 | Astrodome (32-25) | 65-60 | |
| » Starters: Jim Lonborg vs Dave Roberts | Fourth | 12 out |
| Sunday, August 19 |
| » Lost to Phillies (57-66), 5-3 | Astrodome (32-26) | 65-61 | |
| » Starters: Wayne Twitchell vs Jerry Reuss | Fourth | 13 out |
| Monday, August 20 |
| » Defeated Pirates (59-62), 10-2 | Astrodome (33-26) | 66-61 | |
| » Starters: Dock Ellis vs J.R. Richard | Fourth | 12½ out |
| Tuesday, August 21 |
| » Lost to Pirates (60-62), 6-3 | Astrodome (33-27) | 66-62 | |
| » Starters: John Morlan vs Don Wilson | Fourth | 12½ out |
| Wednesday, August 22 |
| » Lost to Pirates (61-62), 4-0 | Astrodome (33-28) | 66-63 | Lost 2 |
| » Starters: Bob Moose vs Tom Griffin | Fourth | 12½ out |
| Thursday, August 23 |
| » Major-league debuts: Matt Alexander (Cubs) |
| Friday, August 24 |
| » Defeated Cubs (61-66), 4-2 | Astrodome (34-28) | 67-63 | |
| » Starters: Burt Hooton vs Jerry Reuss | Fourth | 13 out |
| Saturday, August 25 |
| » Lost to Cubs (62-66), 4-3 | Astrodome (34-29) | 67-64 | |
| » Starters: Rick Reuschel vs Dave Roberts | Fourth | 14 out |
| Sunday, August 26 |
| » Lost to Cubs (63-66), 4-2 | Astrodome (34-30) | 67-65 | Lost 2 |
| » Starters: Fergie Jenkins vs Don Wilson | Fourth | 15 out |
| Monday, August 27 |
| » Lost to Cardinals (66-64), 6-3 | Astrodome (34-31) | 67-66 | Lost 3 |
| » Starters: Mike Nagy vs Tom Griffin | Fourth | 15 out |
| Tuesday, August 28 |
| » Lost to Cardinals (67-64), 8-3 | Astrodome (34-32) | 67-67 | Lost 4 |
| » Starters: Alan Foster vs Jerry Reuss | Fourth | 16 out |
| Wednesday, August 29 |
| » Defeated Cardinals (67-65), 3-2 | Astrodome (35-32) | 68-67 | |
| » Starters: Rick Wise vs Dave Roberts | Fourth | 15 out |
| Thursday, August 30 |
| » Lost to Dodgers (83-51), 6-5 | Dodger Stadium (2-4) | 68-68 | |
| » Starters: Don Wilson vs Al Downing | Fourth | 16 out |
| Friday, August 31 |
| » Defeated Dodgers (83-52), 3-2 | Dodger Stadium (3-4) | 69-68 | |
| » Starters: Tom Griffin vs Doug Rau | Fourth | 15 out |
| Saturday, September 1 |
| » Defeated Dodgers (83-53), 2-0 | Dodger Stadium (4-4) | 70-68 | Won 2 |
| » Starters: Jerry Reuss vs Andy Messersmith | Fourth | 14 out |
| Sunday, September 2 |
| » Defeated Dodgers (83-54), 9-0 | Dodger Stadium (5-4) | 71-68 | Won 3 |
| » Starters: Dave Roberts vs Claude Osteen | Fourth | 13 out |
| » Major-league debuts: Eddie Solomon and Geoff Zahn (Dodgers) |
| Monday, September 3 |
| » Lost to Reds (83-55), 4-3 | Astrodome (35-33) | 71-69 | |
| » Starters: Jack Billingham vs Juan Pizarro | Third | 13 out |
| Tuesday, September 4 |
| » Lost to Reds (84-55), 12-7 | Astrodome (35-34) | 71-70 | Lost 2 |
| » Starters: Don Gullett vs Tom Griffin | Fourth | 14 out |
| Wednesday, September 5 |
| » Lost to Reds (85-55), 9-3 | Astrodome (35-35) | 71-71 | Lost 3 |
| » Starters: Fred Norman vs Jerry Reuss | Fourth | 15 out |
| » Major-league debuts: Mike Easler and Greg Gross (Astros) |
| Friday, September 7 |
| » Lost to Giants (80-59), 9-6 | Candlestick Park (3-4) | 71-72 | Lost 4 |
| » Starters: Dave Roberts vs Tom Bradley | Fourth | 15 out |
| Saturday, September 8 |
| » Defeated Giants (80-60), 9-7 | Candlestick Park (4-4) | 72-72 | |
| » Starters: J.R. Richard vs Ron Bryant | Fourth | 14 out |
| Sunday, September 9 |
| » Defeated Giants (80-61), 5-4 | Candlestick Park (5-4) | 73-72 | Won 2 |
| » Starters: Jerry Reuss vs Jim Barr | Fourth | 14½ out |
| Monday, September 10 |
| » Lost to Padres (53-90), 5-3 | San Diego/Jack Murphy Stadium (3-5) | 73-73 | |
| » Starters: Tom Griffin vs Bill Greif | Fourth | 15 out |
| Tuesday, September 11 |
| » Defeated Padres (53-91), 4-2 | San Diego/Jack Murphy Stadium (4-5) | 74-73 | |
| » Starters: Doug Konieczny vs Randy Jones | Fourth | 15 out |
| » Major-league debuts: Doug Konieczny (Astros) |
| Thursday, September 13 |
| » Lost to Dodgers (85-62), 8-6 | Astrodome (35-36) | 74-74 | |
| » Starters: Tommy John vs Dave Roberts | Fourth | 16 out |
| Friday, September 14 |
| » Lost to Dodgers (86-62), 13-1 | Astrodome (35-37) | 74-75 | Lost 2 |
| » Starters: Andy Messersmith vs Jerry Reuss | Fourth | 17 out |
| Saturday, September 15 |
| » Defeated Dodgers (86-63), 5-1 | Astrodome (36-37) | 75-75 | |
| » Starters: Al Downing vs Tom Griffin | Fourth | 17 out |
| Sunday, September 16 |
| » Defeated Dodgers (86-64), 6-2 | Astrodome (37-37) | 76-75 | Won 2 |
| » Starters: Claude Osteen vs Don Wilson | Fourth | 17 out |
| Monday, September 17 |
| » Defeated Reds (92-58), 5-2 | Riverfront Stadium (3-5) | 77-75 | Won 3 |
| » Starters: Dave Roberts vs Jack Billingham | Fourth | 16 out |
| Tuesday, September 18 |
| » Lost to Reds (93-58), 1-0 | Riverfront Stadium (3-6) | 77-76 | |
| » Starters: Jerry Reuss vs Don Gullett | Fourth | 17 out |
| Future Astro Mitch Meluskey is born in Yakima, WA. |
| Wednesday, September 19 |
| » Defeated Padres (55-96), 8-5 | Astrodome (38-37) | 78-76 | |
| » Starters: Clay Kirby vs Tom Griffin | Fourth | 17½ out |
| » Lost to Padres (56-96), 6-3 | Astrodome (38-38) | 78-77 | |
| » Starters: Rich Troedson vs Doug Konieczny | Fourth | 17½ out |
| Saturday, September 22 |
| » Lost to Braves (74-82), 4-2 | Astrodome (38-39) | 78-78 | Lost 2 |
| » Starters: Carl Morton vs Dave Roberts | Fourth | 18½ out |
| Sunday, September 23 |
| » Lost to Braves (75-82), 10-2 | Astrodome (38-40) | 78-79 | Lost 3 |
| » Starters: Roric Harrison vs Don Wilson | Fourth | 18½ out |
| Monday, September 24 |
| » Defeated Giants (86-71), 10-6 | Astrodome (39-40) | 79-79 | |
| » Starters: Ron Bryant vs Jerry Reuss | Fourth | 18½ out |
| Tuesday, September 25 |
| » Defeated Giants (86-72), 5-1 | Astrodome (40-40) | 80-79 | Won 2 |
| » Starters: John D'Acquisto vs Tom Griffin | Fourth | 18½ out |
| Wednesday, September 26 |
| » Defeated |
