# Swimming at the 2003 World Aquatics Championships – Men's 400 metre individual medley

The Men's 400 Individual Medley event at the 10th FINA World Aquatics Championships swam on July 27, 2003 in Barcelona, Spain. Preliminary heats swam during the morning session, with the top-8 finisher advancing to swim again in the Final that evening.
At the start of the event, the existing World (WR) and Championship (CR) records were both:
* WR: 4:10.73 swum by Michael Phelps (USA) on April 6, 2003 in Indianapolis, USA
* CR: 4:12.30 swum by Tom Dolan (USA) on September 6, 1994 in Rome, Italy

## Results
### Final

| Rank | Swimmer | Nation | Time | Notes |
| 1 | Michael Phelps | United States | 4:09.09 | WR |
| 2 | László Cseh | Hungary | 4:10.79 | |
| 3 | Oussama Mellouli | Tunisia | 4:15.36 | |
| 4 | Tom Wilkens | United States | 4:16.06 | |
| 5 | Massimiliano Rosolino | Italy | 4:17.30 | |
| 6 | Takahiro Mori | Japan | 4:17.54 | |
| 7 | Brian Johns | Canada | 4:20.27 | |
| 8 | Alessio Boggiatto | Italy | 4:21.23 | |

### Preliminaries

| Rank | Heat/Lane | Swimmer | Nation | Time | Notes |
| 1 | H6 L5 | László Cseh | Hungary | 4:14.11 | q |
| 2 | H7 L4 | Michael Phelps | United States | 4:15.72 | q |
| 3 | H5 L4 | Takahiro Mori | Japan | 4:17.12 | q |
| 4 | H7 L3 | Tom Wilkens | United States | 4:17.21 | q |
| 5 | H5 L3 | Oussama Mellouli | Tunisia | 4:18.21 | q |
| 6 | H5 L5 | Brian Johns | Canada | 4:18.33 | q |
| 7 | H6 L4 | Alessio Boggiatto | Italy | 4:18.88 | q |
| 8 | H6 L6 | Massimiliano Rosolino | Italy | 4:19.50 | q |
| 9 | H5 L8 | Cezar Bădiță | Romania | 4:19.72 | |
| 10 | H6 L2 | Robin Francis | Great Britain | 4:20.10 | |
| 11 | H6 L3 | Justin Norris | Australia | 4:20.51 | |
| 11 | H6 L1 | Ioannis Kokkodis | Greece | 4:20.51 | |
| 13 | H7 L2 | Jun Yoshi | Japan | 4:20.52 | |
| 14 | H7 L1 | Igor Berezutskiy | Russia | 4:20.61 | |
| 15 | H7 L6 | István Batházi | Hungary | 4:20.67 | |
| 16 | H7 L5 | Peng Wu | China | 4:20.92 | |
| 17 | H4 L5 | Marko Milenkovič | Slovenia | 4:21.23 | |
| 18 | H5 L6 | Dmytro Nazarenko | Ukraine | 4:21.74 | |
| 19 | H5 L1 | Michael Halika | Israel | 4:21.76 | |
| 20 | H7 L8 | Terence Parkin | South Africa | 4:22.34 | |
| 21 | H6 L8 | Yves Platel | Switzerland | 4:23.16 | |
| 22 | H5 L2 | Trent Steed | Australia | 4:23.29 | |
| 23 | H4 L7 | Vytautas Janušaitis | Lithuania | 4:25.14 | |
| 24 | H4 L3 | Thiago Pereira | Brazil | 4:25.32 | |
| 25 | H4 L4 | Ioannis Drymonakos | Greece | 4:26.07 | |
| 26 | H6 L7 | Carlos Sayao | Canada | 4:26.27 | |
| 27 | H5 L7 | Dean Kent | New Zealand | 4:27.69 | |
| 28 | H4 L8 | Paulius Andrijauskas | Lithuania | 4:27.80 | |
| 29 | H3 L4 | Tao Zhao | China | 4:27.94 | |
| 30 | H4 L1 | Alexei Zatsepine | Russia | 4:28.27 | |
| 31 | H3 L6 | Shilo Ayalon | Israel | 4:28.37 | |
| 32 | H3 L5 | Guntars Deicmanis | Latvia | 4:29.17 | |
| 33 | H3 L2 | Carlo Piccio | Philippines | 4:30.19 | |
| 34 | H3 L3 | Miguel Molina | Philippines | 4:32.27 | |
| 35 | H2 L4 | Vladimir Labzin | Estonia | 4:33.26 | |
| 36 | H4 L6 | Jan Vitazka | Czech Republic | 4:33.52 | |
| 37 | H3 L8 | Yi-Khy Saw | Malaysia | 4:37.21 | |
| 38 | H4 L2 | Mihail Alexandrov | Bulgaria | 4:37.90 | |
| 39 | H3 L7 | Hocine Haciane | Andorra | 4:38.13 | |
| 40 | H2 L2 | Jonathan Mauri | Costa Rica | 4:41.41 | |
| 41 | H2 L7 | Rehan Poncha | India | 4:41.49 | |
| 42 | H2 L5 | Marcos Burgos | Chile | 4:41.55 | |
| 43 | H1 L4 | Kunakorn Yimsomruay | Thailand | 4:44.13 | |
| 44 | H2 L3 | David Cartin | Costa Rica | 4:46.30 | |
| 45 | H2 L6 | Yury Zaharov | Kyrgyzstan | 4:48.33 | |
| 46 | H1 L5 | Dean Palacios | Northern Mariana Islands | 4:55.06 | |
| 47 | H1 L2 | Roy Barahona | Honduras | 4:56.15 | |
| 48 | H2 L1 | Vasilii Danilov | Kyrgyzstan | 4:57.90 | |
| 49 | H1 L3 | Rony Bakale | Republic of the Congo | 5:01.16 | |
| 49 | H1 L1 | Seung Gin Lee | Northern Mariana Islands | 5:01.16 | |
| 51 | H1 L7 | Hei Meng Lao | Macau | 5:10.29 | |
| - | H7 L7 | Nicolas Rostoucher | France | DQ | |
| - | - | George Demetriades | Cyprus | DNS | |
| - | - | Jean-Luc Razakarivony | Madagascar | DNS | |
| - | - | Joao Matias | Angola | DNS | |
| - | - | Chisela Kanchela | Zambia | DNS | |