| August 2008 MLB Debuts |
| DATE | PLAYER | HOMETOWN | POS | AGE | DEBUT | SEASON | CAREER |
| 8/27 | Jesse Chavez, Pit | Victorville, CA | RP | 25 | ChC: 1 IP, 0 ER, 0 H, 1 K | 0-0, 0.00, 1.0 IP, 1 K | 0-0, 0.00, 1.0 IP, 1 K |
| | Andrew Carpenter, Phi | Grants Pass, OR | RP | 23 | NYM: 1 IP, 0 ER, 1 H, 1 K | 0-0, 0.00, 1.0 IP, 1 K | 0-0, 0.00, 1.0 IP, 1 K |
| 8/26 | Chris Lambert, Det | Manchester, NH | SP | 25 | Cle: L, 2.2 IP, 2 ER, 5 H, 2 K | 0-1, 6.75, 2.2 IP, 2 K | 0-1, 6.75, 2.2 IP, 2 K |
| 8/23 | Dirk Hayhurst, SD | Canton, OH | SP | 27 | @SF: 4 IP, 3 ER, 5 H, 2 K | 0-0, 6.75, 4.0 IP, 2 K | 0-0, 6.75, 4.0 IP, 2 K |
| 8/20 | Marco Estrada, Was | Sonora, Mexico | RP | 25 | @Phi: 2 IP, 0 ER, 2 H, 2 K | 0-0, 5.40, 5.0 IP, 6 K | 0-0, 5.40, 5.0 IP, 6 K |
| | Kam Mickolio, Bal | Wolf Point, MT | RP | 24 | Bos: 1 IP, 1 ER, 3 H, 2 K | 0-0, 9.00, 1.0 IP, 2 K | 0-0, 9.00, 1.0 IP, 2 K |
| 8/16 | Matt Palmer, SF | Memphis, TN | RP | 29 | @Atl: L, 2.1 IP, 6 ER, 7 H | 0-2, 8.53, 12.2 IP, 3 K | 0-2, 8.53, 12.2 IP, 3 K |
| | Chad Reineke, SD | Defiance, OH | RP | 26 | Phi: W, 5 IP, 3 ER, 5 H, 5 K | 2-1, 4.50, 16.0 IP, 13 K | 2-1, 4.50, 16.0 IP, 13 K |
| 8/14 | Pablo Sandoval, SF | Puerto Cabello, Venezuela | C | 22 | @Hou: 0-3, RBI | .372, 1 HR, 4 RBI, 5 R | .372, 1 HR, 4 RBI, 5 R |
| 8/13 | Sean Kazmar, SD | Valdosta, GA | SS | 24 | Mil: 1-2 | .077, 1 RBI, 13 AB | .077, 1 RBI, 13 AB |
| | Francisley Bueno, Atl | Havana, Cuba | RP | 27 | ChC: 2.1 IP, 2 ER, 5 H, 1 K | 0-0, 7.71, 2.1 IP, 1 K | 0-0, 7.71, 2.1 IP, 1 K |
| | Ryan Rohlinger, SF | West Bend, WI | SS | 24 | @Hou: 1-4, RBI | .115, 2 RBI, 1 R | .115, 2 RBI, 1 R |
| 8/12 | Charlie Zink, Bos | Carmichael, CA | SP | 28 | Tex: 4.1 IP, 8 ER, 11 H, 1 K | 0-0, 16.62, 4.1 IP, 1 K | |
| | Chris Dickerson, Cin | Hollywood, CA | LF | 26 | @Pit: 1-4, run, SB | .308, 3 HR, 6 RBI, 8 R, 3 SB | .308, 3 HR, 6 RBI, 8 R, 3 SB |
| | Cliff Pennington, Oak | Corpus Christi, TX | SS | 24 | TB: 0-3 | .154, 2 RBI, 3 R, 1 SB | .154, 2 RBI, 3 R, 1 SB |
| 8/09 | Adam Rosales, Cin | Chicago, IL | SS | 25 | Hou: 0-1 | .125, 8 AB | .125, 8 AB |
| 8/06 | Gio Gonzalez, Oak | Hialeah, FL | SP | 22 | @Tor: L, 6 IP, 4 ER, 4 H, 4 K | 1-2, 7.25, 22.1 IP, 22 K | 1-2, 7.25, 22.1 IP, 22 K |
| 8/05 | Chris Waters, Bal | Lakeland, FL | RP | 27 | @LAA: W, 8 IP, 0 ER, 1 H, 3 K | 2-1, 4.71, 28.2 IP, 12 K | 2-1, 4.71, 28.2 IP, 12 K |
| 8/04 | Steven Register, Col | Columbus, GA | SP | 25 | Was: 0.1 IP, 0 ER, 0 H, 1 K | 0-0, 0.00, 0.1 IP, 1 K | 0-0, 0.00, 0.1 IP, 1 K |
| 8/03 | Eddie Kunz, NYM | Portland, OR | RP | 22 | @Hou: 1 IP, 0 ER, 1 H | 0-0, 13.50, 2.2 IP, 1 K | 0-0, 13.50, 2.2 IP, 1 K |
| 8/02 | Daniel Murphy, NYM | Jacksonville, FL | 3B | 23 | @Hou: 1-4, run | .328, 2 HR, 13 RBI, 12 R | .328, 2 HR, 13 RBI, 12 R |
| 8/01 | Tommy Hunter, Tex | Tuscaloosa, AL | SP | 22 | Tor: 5 IP, 6 ER, 8 H, 4 K | 0-2, 16.36, 11.0 IP, 9 K | 0-2, 16.36, 11.0 IP, 9 K |
| | Randy Ruiz, Min | Bronx, NY | 1B | 30 | Cle: 1-3, run | .340, 1 HR, 6 RBI, 11 R | .340, 1 HR, 6 RBI, 11 R |