| 1 | Antonio McKay | USA | 46,06 | Q |
| 2 | Cayetano Cornet | ESP | 46,30 | Q |
| 3 | Ian Morris | TRI | 46,52 | Q |
| 4 | Alemayehu Gudeta | ETH | 46,96 | |
| 5 | Jörg Vaihinger | FRG | 47,01 | |
| 6 | Howard Burnett | JAM | 47,18 |
| 1 | Slobodan Brankovic | YUG | 46,49 | Q |
| 2 | Gabriel Tiacoh | CIV | 46,69 | Q |
| 3 | Brian Whittle | GBR | 46,71 | Q |
| 4 | Arjan Vissermann | NED | 46,94 | |
| 5 | Clarence Daniel | USA | 47,03 | |
| 6 | Bertland Cameron | JAM | 47,78 |