| May 1 | NL | | 26 | Diamondbacks 5, Brewers 2Final | Diamondbacks rally to beat the Brewers 5-2 |
| May 2 | NL | | 20 | Diamondbacks 4, Brewers 1Final | Haren dominant in D'backs win over Brewers |
| May 3 | NL | | 55 | Diamondbacks 3, Brewers 4Final | Brewers blow lead but regroup to beat Arizona |
| May 4 | NL | | | Diamondbacks 2, Dodgers 7Final | Dodgers improve to 11-0 at home, beat Arizona 7-2 |
| May 5 | NL | | 15 | Diamondbacks 1, Dodgers 3Final | Dodgers tie ML record with 12-0 start at home |
| May 6 | NL | | 38 | Diamondbacks 3, Padres 1Final | Upton homers twice, Diamondbacks beat Pads 3-1 |
| May 7 | NL | | 140 | Diamondbacks 3, Padres 4Final/10 | Eckstein's 10th-inning single gives Padres 4-3 win |
| May 8 | NL | | 74 | Nationals 5, Diamondbacks 4Final | Flores, Nats spoil Hinch's debut in Arizona 5-4 |
| May 9 | NL | | 69 | Nationals 2, Diamondbacks 1Final | Zimmerman homers to extend streak; Nats win again |
| May 10 | NL | | 10 | Nationals 8, Diamondbacks 10Final | Snyder, Byrnes give Hinch first win with D-backs |
| May 11 | NL | | | Reds 13, Diamondbacks 5Final | Taveras leads Reds past Diamondbacks 13-5 |
| May 12 | NL | | 21 | Reds 3, Diamondbacks 1Final | Owings dominates as Reds beat Diamondbacks 3-1 |
| May 13 | NL | | 10 | Reds 10, Diamondbacks 3Final | Phillips, Cueto lead Reds to sweep of D-backs |
| May 15 | NL | | 137 | Diamondbacks 3, Braves 4Final | Braves recover in 9th, beat Arizona 4-3 |
| May 16 | NL | | | Diamondbacks 12, Braves 0Final | Scherzer, Diamondbacks blank Braves 12-0 |
| May 17 | NL | | | Diamondbacks 0, Braves 0Final | D-backs-Braves game postponed by rain |
| May 18 | NL | | 10 | Diamondbacks 0, Marlins 1Final | Diamondbacks-Marlins game postponed by rain |
| May 19 | NL | | 49 | Diamondbacks 5, Marlins 3Final | Reynolds homers to lead Diamondbacks to 5-3 win |
| May 20 | NL | | 147 | Diamondbacks 11, Marlins 9Final/13 | Upton helps Diamondbacks split doubleheader |
| May 20 | NL | | | Diamondbacks 6, Marlins 8Final | Uggla leads Marlins past Diamondbacks |
| May 21 | NL | | 40 | Diamondbacks 4, Marlins 3Final | Reynolds' homer lifts Arizona past Marlins 4-3 |
| May 22 | ML | | 77 | Diamondbacks 2, Athletics 1Final | Young, Buckner lead D'backs over A's |
| May 23 | ML | | 135 | Diamondbacks 8, Athletics 7Final/11 | Giambi hits 400th homer, but A's lose |
| May 24 | ML | | 10 | Diamondbacks 2, Athletics 6Final | Giambi homers again, this time A's win |
| May 25 | NL | | 135 | Padres 9, Diamondbacks 7Final/10 | Headley's homer help Padres win 10th in a row |
| May 26 | NL | | 45 | Padres 5, Diamondbacks 6Final | Diamondbacks end Padres' 10-game winning streak |
| May 27 | NL | | 5 | Padres 8, Diamondbacks 5Final | Gonzalez leads Padres to 8-5 victory over DBacks |
| May 28 | NL | | 5 | Braves 2, Diamondbacks 5Final | Haren, Diamondbacks beat Lowe, Braves 5-2 |
| May 29 | NL | | 10 | Braves 10, Diamondbacks 6Final | Braves hold off Diamondbacks 10-6 |
| May 30 | NL | | 155 | Braves 2, Diamondbacks 3Final/11 | Byrnes' single gives Arizona 3-2 win in 11 innings |
| May 31 | NL | | | Braves 9, Diamondbacks 3Final | Jones homers, drives in 4 to lead Braves |