| Final | time | | L | React. | bib | | 1. C. Fredericks |  RSA | 48.50s | | 1 | 0.156s | 2098 | | 2. J. Gordon |  TTO | 48.75s | SB | 3 | 0.170s | 2363 | | 3. J. Gibson |  BAH | 48.78s | NR | 5 | 0.159s | 1151 | | 4. N. Flannery |  ENG | 49.46s | | 1 | 0.160s | 1395 | | 5. C. Cuevas-morton |  NGR | 49.65s | | 2 | 0.225s | 1947 | | 6. B. Mucheru |  KEN | 49.99s | | 8 | 0.167s | 1768 | | 7. R. Yates | ENG | 50.13s | | 6 | 0.187s | 1493 | | -. A. Whyte |  JAM | DNF | | 6 | | 1708 |
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| | | First 2 and Best 2 progressed to Final. |
| Heat 1 | time | | L | React. | bib | | 1. J. Gordon | TTO | 49.42s | | 3 | 0.161s | 2363 | | 2. A. Whyte | JAM | 49.58s | | 2 | 0.193s | 1708 | | 3. C. Cuevas-morton | NGR | 49.62s | | 1 | 0.193s | 1947 | | 4. N. Flannery | ENG | 49.97s | | 7 | 0.159s | 1395 | | 5. N. Bett | KEN | 51.21s | | 6 | 0.182s | 1730 | | -. K. Couto |  MOZ | DQ | | 5 | | 1882 | | -. S. Viliamu Sepa |  SAM | | | 4 | | 2138 |
| Heat 2 | time | | L | React. | bib | | 1. C. Fredericks | RSA | 49.26s | | 3 | 0.159s | 2098 | | 2. J. Gibson | BAH | 49.66s | | 4 | 0.160s | 1151 | | 3. I. Dewhurst |  AUS | 50.45s | | 5 | 0.173s | 1049 | | 4. S. Rodger | ENG | 50.71s | | 6 | 0.193s | 1455 | | 5. J. Harvey |  NIR | 52.06s | | 1 | 0.213s | 2000 | | -. M. Boino |  PNG | DQ | | 2 | | 2067 | | -. L. Green | JAM | DQ | | 7 | | 1669 |
| Heat 3 | time | | L | React. | bib | | 1. B. Mucheru | KEN | 49.67s | | 7 | 0.188s | 1768 | | 2. R. Yates | ENG | 49.80s | | 5 | 0.202s | 1493 | | 3. L. van Zyl | RSA | 50.07s | | 3 | 0.179s | 2113 | | 4. D. Greene |  WAL | 50.36s | | 6 | 0.170s | 2423 | | 5. E. Mayers | TTO | 50.51s | | 2 | 0.183s | 2370 | | 6. W. Gime | PNG | 53.62s | | 4 | 0.209s | 2071 | | -. R. Cato | JAM | DQ | | 1 | | 1655 |
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| Lane Heat 1 | PB | SB | bib | | 1. C. Cuevas-morton | NGR | 49.39 s | 48.79s | 1947 | | 2. A. Whyte | JAM | 48.58 s | 48.58s | 1708 | | 3. J. Gordon | TTO | 49.29 s | 47.69s | 2363 | | 4. S. Viliamu Sepa | SAM | 54.25 s | 54.25s | 2138 | | 5. K. Couto | MOZ | 49.56 s | 49.02s | 1882 | | 6. N. Bett | KEN | 49.75 s | 49.70s | 1730 | | 7. N. Flannery | ENG | 48.80 s | 48.80s | 1395 |
| Lane Heat 2 | PB | SB | bib | | 1. J. Harvey | NIR | 50.64s | 50.13s | 2000 | | 2. M. Boino | PNG | 52.56s | 50.37s | 2067 | | 3. C. Fredericks | RSA | 48.42s | 48.14s | 2098 | | 4. J. Gibson | BAH | 48.95s | 48.95s | 1151 | | 5. I. Dewhurst | AUS | 49.52s | 49.52s | 1049 | | 6. S. Rodger | ENG | 49.51s | 49.19s | 1455 | | 7. L. Green | JAM | 49.00s | 48.47s | 1669 |
| Lane Heat 3 | PB | SB | bib | | 1. R. Cato | JAM | 48.48 s | 48.48s | 1655 | | 2. E. Mayers | TTO | 49.57 s | 49.57s | 2370 | | 3. L. van Zyl | RSA | 48.96 s | 47.66s | 2113 | | 4. W. Gime | PNG | 52.95 s | 51.71s | 2071 | | 5. R. Yates | ENG | 49.46 s | 49.06s | 1493 | | 6. D. Greene | WAL | 49.89 s | 47.84s | 2423 | | 7. B. Mucheru | KEN | 49.25 s | 49.25s | 1768 |
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