Records
Prior to the competition, the established records were as follows.
Results
| KEY: |
q | Fastest non-qualifiers |
Q | Qualified |
WR | World record |
AR | Area record |
NR | National record |
PB | Personal best |
SB | Seasonal best |
|
Heats
Qualification: First 3 in each heat (Q) and the next 3 fastest (q) advance to the semifinals.
| Rank | Heat | Name | Nationality | Time | Notes |
| 1 | 1 | Chris Brown |  Bahamas | 44.50 | Q, SB |
| 2 | 4 | LaShawn Merritt |  United States | 44.78 | Q |
| 3 | 1 | John Steffensen |  Australia | 44.82 | Q, SB |
| 4 | 1 | Arismendy Peguero |  Dominican Republic | 44.92 | Q, PB |
| 5 | 4 | Johan Wissman |  Sweden | 44.94 | Q, NR |
| 6 | 3 | Alleyne Francique |  Grenada | 44.95 | Q, SB |
| 7 | 6 | Nery Brenes |  Costa Rica | 45.01 | Q, NR |
| 8 | 2 | Jeremy Wariner | United States | 45.10 | Q |
| 9 | 6 | Angelo Taylor | United States | 45.13 | Q |
| 10 | 7 | Tyler Christopher |  Canada | 45.15 | Q |
| 11 | 3 | Leslie Djhone |  France | 45.17 | Q |
| 12 | 5 | Gary Kikaya |  Democratic Republic of the Congo | 45.21 | Q |
| 13 | 7 | Ato Modibo |  Trinidad and Tobago | 45.22 | Q, SB |
| 14 | 2 | Avard Moncur | Bahamas | 45.27 | Q |
| 15 | 5 | Sanjay Ayre |  Jamaica | 45.28 | Q |
| 16 | 6 | William Collazo |  Cuba | 45.29 | Q, PB |
| 17 | 4 | Andrae Williams | Bahamas | 45.31 | Q |
| 18 | 3 | Ricardo Chambers | Jamaica | 45.34 | Q |
| 19 | 2 | David Gillick |  Ireland | 45.35 | Q |
| 20 | 6 | California Molefe |  Botswana | 45.36 | q, SB |
| 21 | 7 | Sean Wroe | Australia | 45.39 | Q |
| 22 | 4 | Young Talkmore Nyongani |  Zimbabwe | 45.40 | q, SB |
| 23 | 5 | Timothy Benjamin |  United Kingdom | 45.44 | Q |
| 23 | 6 | Michael Blackwood | Jamaica | 45.44 | q |
| 23 | 1 | Bastian Swillims |  Germany | 45.44 | PB |
| 26 | 5 | Chris Lloyd |  Dominica | 45.46 | |
| 27 | 2 | Martyn Rooney | United Kingdom | 45.47 | SB |
| 28 | 2 | Lewis Banda | Zimbabwe | 45.47 | SB |
| 29 | 7 | Daniel Dąbrowski |  Poland | 45.50 | |
| 30 | 3 | Andrew Steele | United Kingdom | 45.54 | |
| 31 | 5 | Vladislav Frolov |  Russia | 45.69 | |
| 32 | 1 | Renny Quow | Trinidad and Tobago | 45.70 | |
| 33 | 7 | Andrea Barberi |  Italy | 45.74 | SB |
| 34 | 1 | Marcin Marciniszyn | Poland | 45.83 | |
| 35 | 3 | Rafał Wieruszewski | Poland | 45.94 | SB |
| 36 | 3 | Carlos Santa | Dominican Republic | 45.99 | SB |
| 37 | 2 | Brice Panel | France | 46.02 | |
| 38 | 3 | Clemens Zeller |  Austria | 46.06 | |
| 39 | 1 | Dimitrios Regas |  Greece | 46.22 | SB |
| 40 | 6 | Yuki Yamaguchi |  Japan | 46.28 | |
| 41 | 4 | Eric Milazar |  Mauritius | 46.55 | |
| 42 | 5 | Ioan Vieru |  Romania | 46.78 | |
| 43 | 4 | Andrés Silva |  Uruguay | 46.79 | |
| 44 | 2 | Félix Martínez |  Puerto Rico | 46.86 | |
| 45 | 1 | Takeshi Fujiwara |  El Salvador | 46.92 | NR |
| 46 | 7 | Dimitrios Gravalos | Greece | 46.94 | |
| 47 | 5 | Mathieu Gnanligo |  Benin | 47.51 | |
| 48 | 6 | Jonathon Lavers |  Gibraltar | 47.97 | NR |
| 49 | 6 | Ivano Bucci |  San Marino | 48.07 | PB |
| 50 | 5 | Nicolau Palanca |  Angola | 48.60 | |
| 51 | 4 | Dalibor Spasovski |  Macedonia | 48.63 | PB |
| 52 | 7 | Moses Kamut |  Vanuatu | 48.90 | |
| 53 | 4 | Karar A.M. Al Abbody | .svg.png) Iraq | 48.95 | PB |
| 54 | 2 | Abdulla Mohamed Hussein |  Somalia | 50.54 | PB |
| 55 | 2 | Hermán López |  Nicaragua | 50.72 | |
| 3 | Yuzo Kanemaru | Japan | | DNF |
| 6 | Nagmeldin Ali Abubakr |  Sudan | | DNF |
| 7 | Lionel Larry | United States | | DNF |
| 4 | Gakologelwang Masheto | Botswana | | DNS |
| 5 | Hamdan Al-Bishi |  Saudi Arabia | | DNS |
Semifinals
First 2 in each semifinal (Q) and the next 2 fastest (q) advance to the final.
