| Final | time | | | 1. Antonio McKay |  USA | 45.59s | | | 2. Ian Morris |  TRI | 46.09s | | | 3. Cayetano Cornet |  ESP | 46.40s | | | 4. Slobodan Brankovic |  YUG | 46.48s | | | 5. Brian Whittle |  GBR | 46.78s | | | 6. Gabriel Tiacoh |  CIV | 47.35s | |
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| | | First 3 advanced to Final |
| Semi 1 | time | | | 1. Antonio McKay | USA | 46.06s | Q | | 2. Cayetano Cornet | ESP | 46.30s | Q | | 3. Ian Morris | TRI | 46.52s | Q | | 4. Alemayehu Gudeta |  ETH | 46.96s | | | 5. Jörg Vaihinger |  FRG | 47.01s | | | 6. Howard Burnett |  JAM | 47.18s | |
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| Semi 2 | time | | | 1. Slobodan Brankovic | YUG | 46.49s | Q | | 2. Gabriel Tiacoh | CIV | 46.69s | Q | | 3. Brian Whittle | GBR | 46.71s | Q | | 4. Arjan Vissermann |  NED | 46.94s | | | 5. Clarence Daniel | USA | 47.03s | | | 6. Bertland Cameron | JAM | 47.78s | |
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| Heat 1 | time | | | 1. Antonio McKay | USA | 46.86s | Q | | 2. Ian Morris | TRI | 47.09s | Q | | 3. Arjan Vissermann | NED | 47.11s | q | | 4. Antonio Sanchez | ESP | 47.60s | | | 5. Juan Pablo Toledo |  MEX | 48.65s | |
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| Heat 2 | time | | | 1. Howard Burnett | JAM | 46.91s | Q | | 2. Jörg Vaihinger | FRG | 47.00s | Q | | 3. Gusztav Menczer |  HUN | 47.43s | | | 4. Romeo Gido |  PHI | 47.63s | | | 5. Patrick Delice | TRI | 47.86s | | | 6. Ahmed Abdel Ghanem |  EGY | 48.63s | |
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| Heat 3 | time | | | 1. Cayetano Cornet | ESP | 46.64s | Q | | 2. Alemayehu Gudeta | ETH | 47.14s | Q | | 3. Todd Bennett | GBR | 47.35s | | | 4. Tomasz Jedrusik |  POL | 47.36s | | | 5. Karsten Just | FRG | 47.67s | |
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| Heat 4 | time | | | 1. Gabriel Tiacoh | CIV | 47.00s | Q | | | 2. Clarence Daniel | USA | 47.20s | Q | | | 3. Takahiro Watanabe |  JPN | 47.97s | | | | 4. Troy Douglas |  BER | 48.46s | | | | 5. Gerson de Andrade Souza |  BRA | 49.04s | | |
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| Heat 5 | time | | | 1. Brian Whittle | GBR | 46.69s | Q | | | 2. Slobodan Brankovic | YUG | 46.69s | Q | | | 3. Bertland Cameron | JAM | 46.93s | q | | | 4. Ervin Katona | HUN | 47.33s | | | | 5. Anton Skerritt |  CAN | 47.69s | | |
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