The Men's 4x400 metres relay event at the 2003 IAAF World Indoor Championships was held on March 15–16.
* Runners who participated in the heats only and received medals.
Note: The United States (James Davis, Jerome Young, Milton Campbell, Tyree Washington) originally won the 4x400&m gold medal in 3:04.09, but were disqualified after Young admitted to the use of banned substances.
Qualification: First 2 teams of each heat (Q) plus the next 2 fastest (q) advance to the final.