Themen's1500 metres event at the2003 IAAF World Indoor Championships was held on 14–15 March 2003.
The winning margin was 0.03 seconds which as of July 2024 remains the joint-narrowest winning margin in the men's 1500 metres at these championships.
| Gold | Silver | Bronze |
Driss Maazouzi France | Bernard Lagat Kenya | Abdelkader Hachlaf Morocco |
First 2 of each heat (Q) and next 3 fastest (q) qualified for the semifinals.
| Rank | Heat | Name | Nationality | Time | Notes |
|---|---|---|---|---|---|
| 1 | 2 | Bernard Lagat | Kenya | 3:39.97 | Q |
| 2 | 2 | Roberto Parra |  Spain | 3:40.40 | Q |
| 3 | 2 | Ivan Heshko |  Ukraine | 3:40.61 | q |
| 4 | 2 | Andrey Zadorozhniy |  Russia | 3:40.80 | q, SB |
| 5 | 2 | James Nolan |  Ireland | 3:40.85 | q |
| 6 | 2 | Mirosław Formela |  Poland | 3:40.89 | PB |
| 7 | 3 | Cornelius Chirchir | Kenya | 3:41.08 | Q |
| 8 | 2 | James Thie |  Great Britain | 3:41.18 | PB |
| 9 | 3 | Juan Carlos Higuero | Spain | 3:41.37 | Q, SB |
| 10 | 3 | Julius Achon |  Uganda | 3:41.85 | SB |
| 11 | 3 | Anis Selmouni | Morocco | 3:41.99 | |
| 12 | 3 | Tarek Boukensa |  Algeria | 3:42.88 | |
| 13 | 3 | Jason Lunn |  United States | 3:43.31 | |
| 14 | 3 | Christian Obrist |  Italy | 3:43.97 | |
| 15 | 3 | Philippe Bandi |  Switzerland | 3:44.37 | |
| 16 | 2 | Salvatore Vincenti | Italy | 3:45.93 | |
| 17 | 2 | Luís Feiteira |  Portugal | 3:46.99 | |
| 18 | 1 | Driss Maazouzi | France | 3:48.36 | Q |
| 19 | 1 | Abdelkader Hachlaf | Morocco | 3:48.39 | Q |
| 20 | 1 | Rui Silva | Portugal | 3:48.41 | |
| 21 | 1 | Michal Šneberger |  Czech Republic | 3:48.65 | |
| 22 | 1 | Michael Stember | United States | 3:48.71 | |
| 23 | 1 | Michael East | Great Britain | 3:49.31 | |
| 24 | 1 | Zbigniew Graczyk | Poland | 3:49.39 | |
| 25 | 1 | Graham Hood |  Canada | 3:50.86 | |
| 26 | 3 | Abdillahi Bouh Moumin |  Djibouti | 4:15.51 | NR |
| Rank | Name | Nationality | Time | Notes |
|---|---|---|---|---|
 | Driss Maazouzi | France | 3:42.59 | |
 | Bernard Lagat | Kenya | 3:42.62 | |
 | Abdelkader Hachlaf | Morocco | 3:42.71 | |
| 4 | Cornelius Chirchir | Kenya | 3:43.03 | |
| 5 | Ivan Heshko | Ukraine | 3:44.56 | |
| 6 | James Nolan | Ireland | 3:44.67 | |
| 7 | Andrey Zadorozhniy | Russia | 3:44.80 | |
| 8 | Juan Carlos Higuero | Spain | 3:44.81 | |
| 9 | Roberto Parra | Spain | 3:47.44 |
