| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | 
|---|---|---|---|---|---|---|
| 1 | 1 | 2 | 243 | Isaac MAKWALA |  BOT | 44.11 Q | 
| 2 | 1 | 1 | 580 | Kirani JAMES |  GRN | 44.16 Q | 
| 3 | 2 | 1 | 410 | LuguelÃn SANTOS |  DOM | 44.26 Q NR | 
| 4 | 1 | 3 | 857 | Wayde VAN NIEKERK |  RSA | 44.31 Q | 
| 5 | 2 | 3 | 1047 | LaShawn Merritt |  USA | 44.34 Q SB | 
| 6 | 2 | 2 | 715 | Youssef Ahmed MASRAHI |  KSA | 44.40 Q | 
| 7 | 3 | 2 | 520 | Rabah YOUSIF |  GBR | 44.54 q PB | 
| 8 | 3 | 3 | 938 | Machel CEDENIO |  TTO | 44.64 q | 
| 9 | 4 | 2 | 940 | Lalonde Gordon |  TTO | 44.70 | 
| 10 | 3 | 1 | 1067 | David Verburg |  USA | 44.71 | 
| 11 | 4 | 1 | 216 | Kévin BORLÉE |  BEL | 44.74 SB | 
| 12 | 5 | 2 | 1049 | Bryshon Nellum |  USA | 44.77 | 
| 12 | 4 | 3 | 627 | Javon FRANCIS |  JAM | 44.77 | 
| 14 | 5 | 3 | 217 | Jonathan BORLÉE |  BEL | 44.85 | 
| 15 | 6 | 2 | 631 | Rusheen MCDONALD |  JAM | 44.86 | 
| 16 | 7 | 2 | 194 | Steven GARDINER |  BAH | 44.98 | 
| 16 | 5 | 1 | 943 | Renny QUOW |  TTO | 44.98 | 
| 18 | 6 | 1 | 1050 | Vernon NORWOOD |  USA | 45.07 | 
| 18 | 7 | 1 | 189 | Chris Brown |  BAH | 45.07 | 
| 20 | 6 | 3 | 521 | Martyn ROONEY |  GBR | 45.29 | 
| 21 | 8 | 2 | 362 | Nery Brenes |  CRC | 45.41 | 
| 22 | 8 | 1 | 632 | Peter Matthews |  JAM | 45.42 | 
| 23 | 7 | 3 | 204 | Michael Mathieu |  BAH | 45.43 | 
| 24 | 8 | 3 | 759 | Liemarvin BONEVACIA |  NED | 45.65 |