The current men's world record is held by Michael Johnson, with a time of 43.18 seconds. The world indoor record holder is Kerron Clement, in 44.57 seconds. The current women's world record is held by Marita Koch, with a time of 47.60 seconds (set before the advent of out-of-competition testing). The reigning Olympic champions are LaShawn Merritt and Christine Ohuruogu. The Paralympic world record of 46.56 seconds is held by Oscar Pistorius.
(Updated 3 October 2008.)
| Rank | Time | Athlete | Nation | Date | Location |
|---|---|---|---|---|---|
| 1. | 43.18 | Michael Johnson | 26 August 1999 | Seville | |
| 2. | 43.29 | Harry 'Butch' Reynolds | 17 August 1988 | Zürich | |
| 3. | 43.45 | Jeremy Wariner | 31 August 2007 | Osaka | |
| 4. | 43.50 | Quincy Watts | 5 August 1992 | Barcelona | |
| 5. | 43.75 | LaShawn Merritt | 21 August 2008 | Beijing | |
| 6. | 43.81 | Danny Everett | 26 June 1992 | New Orleans | |
| 7. | 43.86 | Lee Evans | 18 October 1968 | Mexico City | |
| 8. | 43.87 | Steve Lewis | 28 September 1988 | Seoul | |
| 9. | 43.97 | Larry James | 18 October 1968 | Mexico City | |
| 10. | 44.05 | Angelo Taylor | 29 February 2007 | Indianapolis |
(Updated 3 October 2008.)
| Rank | Time | Athlete | Nation | Date | Location |
|---|---|---|---|---|---|
| 1. | 47.60 | Marita Koch | 6 October 1985 | Canberra | |
| 2. | 47.99 | Jarmila Kratochvílová | 10 August 1983 | Helsinki | |
| 3. | 48.25 | Marie-José Pérec | 29 July 1996 | Atlanta | |
| 4. | 48.27 | Olga Vladykina-Bryzgina | 6 October 1985 | Canberra | |
| 5. | 48.59 | Taťána Kocembová | 10 August 1983 | Helsinki | |
| 6. | 48.63 | Cathy Freeman | 29 July 1996 | Atlanta | |
| 7. | 48.70 | Sanya Richards | 16 September 2006 | Athens | |
| 8. | 48.83 | Valerie Brisco-Hooks | 6 August 1984 | Los Angeles | |
| 9. | 48.89 | Ana Guevara | 27 August 2003 | Paris Saint-Denis | |
| 10. | 49.05 | Chandra Cheeseborough | 6 August 1984 | Los Angeles |