| Final | time | age | | 1. Alberto Juantorena |  CUB | 44.26s | 25 | | 2. Fred Newhouse |  USA | 44.40s | 27 | | 3. Herman Frazier | USA | 44.95s | 21 | | 4. Alfons Brijdenbach |  BEL | 45.04s | 21 | | 5. Maxie Parks | USA | 45.24s | 25 | | 6. Richard Mitchell |  AUS | 45.40s | 21 | | 7. David Jenkins |  GBR | 45.57s | 24 | | 8. Jan Werner |  POL | 45.63s | 29 |
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| Semi 1 | time | | 1. Alberto Juantorena | CUB | 45.10s | | 2. Alfons Brijdenbach | BEL | 45.28s | | 3. Maxie Parks | USA | 45.61s | | 4. Richard Mitchell | AUS | 45.69s | | 5. Bernd Hermann |  FRG | 45.94s | | 6. Brian Saunders |  CAN | 46.46s | | 7. Alfonso Diguida |  ITA | 46.50s | | 8. Delmo Da Silva |  BRA | 46.69s |
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| Semi 2 | time | | 1. Fred Newhouse | USA | 44.89s | | 2. David Jenkins | GBR | 45.20s | | 3. Herman Frazier | USA | 45.24s | | 4. Jan Werner | POL | 45.44s | | 5. Jerzy Pietrzyk | POL | 45.65s | | 6. Franz-P. Hofmeister | FRG | 46.05s | | 7. Michael Solomon |  TRI | 46.20s | | 8. Karl Honz | FRG | 46.63s |
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| Quarter 1 | time | | 1. Herman Frazier | USA | 46.52s | | 2. Alfons Brijdenbach | BEL | 46.56s | | 3. Karl Honz | FRG | 46.94s | | 4. Alfonso Diguida | ITA | 47.07s | | 5. Ossi Karttunen |  FIN | 47.45s | | 6. Peter Grant | AUS | 47.69s | | 7. Alfred Daley |  JAM | 48.46s | | 8. Glenn Bogue | CAN | 48.98s |
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| Quarter 2 | time | | 1. Richard Mitchell | AUS | 45.76s | | 2. Alberto Juantorena | CUB | 45.92s | | 3. Jerzy Pietrzyk | POL | 46.30s | | 4. Brian Saunders | CAN | 46.42s | | 5. Leighton Priestley | JAM | 46.45s | | 6. Michael Sands |  BAH | 46.48s | | 7. Ivan Mangual |  PUR | 46.56s | | 8. Charles Joseph | TRI | 46.61s |
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| Quarter 3 | time | | 1. Michael Solomon | TRI | 45.83s | | 2. Jan Werner | POL | 45.88s | | 3. Maxie Parks | USA | 45.99s | | 4. Bernd Herrmann | FRG | 46.07s | | 5. Markku Kukkoaho | FIN | 46.24s | | 6. Eddy Gutierrez | CUB | 46.65s | | 7. Glendon Cohen | GBR | 47.67s | | -.Don Domansky | CAN | DNS |
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| Quarter 4 | time | | 1. Fred Newhouse | USA | 45.97s | | 2. David Jenkins | GBR | 46.18s | | 3. Franz-P. Hofmeister | FRG | 46.20s | | 4. Delmo Da Silva | BRA | 46.48s | | 5. Josko Alebic |  YUG | 46.94s | | 6. Zbigniew Jaremski | POL | 47.10s | | 7. Fred Sowerby |  ANT | 48.03s | | 8. Raymond Heerenveen |  AHO | 48.88s |
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| Heat 1 | time | | 1. Herman Frazier | USA | 46.09s | | 2. Michael Sands | BAH | 46.52s | | 3. Zbigniew Jaremski | POL | 46.68s | | 4. Peter Grant | AUS | 47.03s | | 5. Brian Saunders | CAN | 47.24s | | 6. Carlos Norona | CUB | 48.46s | | 7. Hamil Grimes |  BAR | 49.24s | | 8. Wilfrid Cyriaque |  HAI | 51.49s |
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| Heat 2 | time | | 1. Fred Newhouse | USA | 45.42s | | 2. Richard Mitchell | AUS | 46.11s | | 3. Jan Werner | POL | 46.19s | | 4. Alfonso Diguida | ITA | 46.52s | | 5. Leighton Priestley | JAM | 46.74s | | 6. Don Domansky | CAN | 47.24s | | 7. Errol Thurton |  BIZ | 48.91s | | 8. Ahmed Asiry |  KSA | 49.72s |
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| Heat 3 | time | | 1. Maxie Parks | USA | 46.12s | | 2. Delmo Da Silva | BRA | 47.21s | | 3. Ivan Mangual | PUR | 47.39s | | 4. Karl Honz | FRG | 47.47s | | 5. Eddy Gutierrez | CUB | 47.89s | | 6. Renelda Swan |  BER | 49.13s | | -.Stavros Tziortzis |  GRE | DNS | | -.Antony Moore |  FIJ | DNS |
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| Heat 4 | time | | 1. Alfons Brijdenbach | BEL | 46.73s | | 2. Jerzy Pietrzyk | POL | 46.92s | | 3. Franz-P. Hofmeister | FRG | 47.17s | | 4. Ossi Karttunen | FIN | 47.22s | | 5. Glenn Bogue | CAN | 47.42s | | 6. Raymond Heerenveen | AHO | 47.44s | | 7. Wavala Kali |  NGY | 48.85s | | 8. Ricardo Larios |  NCA | 50.52s |
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| Heat 5 | time | | 1. David Jenkins | GBR | 46.60s | | 2. Bernd Herrmann | FRG | 46.99s | | 3. Josko Alebic | YUG | 47.03s | | 4. Markku Kukkoaho | FIN | 47.67s | | 5. Charles Joseph | TRI | 47.72s | | 6. Samba Dieye |  SEN | 47.98s | | 7. Bjarni Stefansson |  ISL | 48.34s |
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| Heat 6 | time | | 1. Michael Solomon | TRI | 47.29s | | 2. Glendon Cohen | GBR | 47.77s | | 3. Alberto Juantorena | CUB | 47.89s | | 4. Alfred Daley | JAM | 48.04s | | 5. Fred Sowerby | ANT | 48.12s | | 6. Avognan Nogboun |  CIV | 48.24s | | 7. Jose Jesus Carvalho |  POR | 48.47s |
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