2003 IAAF World Indoor Championships – Men's 400 metres

First 2 of each heat (Q) and next 4 fastest (q) qualified for the semifinals.

Rank	Heat	Name	Nationality	Time	Notes
1	1	Daniel Caines	Great Britain	45.85	Q
2	1	Tyree Washington	United States	45.90	Q, PB
3	4	Daniel Batman	Australia	46.11	Q
4	1	Marek Plawgo	Poland	46.33	q
5	2	David Canal	Spain	46.39	Q
6	3	Jamie Baulch	Great Britain	46.44	Q
7	1	Sofiane Labidi	Tunisia	46.47	q, NR
8	2	Paul McKee	Ireland	46.68	Q
9	3	David McCarthy	Ireland	46.69	Q
10	3	Chris Brown	Bahamas	46.74	q
11	3	Cedric van Branteghem	Belgium	46.75	q
12	4	Ioan Lucian Vieru	Romania	46.84	Q
13	4	Damion Barry	Trinidad and Tobago	47.21
14	2	Edoardo Vallet	Italy	47.77
15	2	California Molefe	Botswana	47.90	NR
16	4	Dmitriy Chumichkin	Azerbaijan	48.11
17	2	Ernie Candelario	Philippines	48.86
18	3	Román Basil	Panama	49.46
	1	Rohan Pradeep Kumara	Sri Lanka	DQ
	2	Davian Clarke	Jamaica	DQ
	3	Moses Kondowe	Malawi	DQ
	4	Corey Nelson	United States	DQ
	4	Alleyne Francique	Grenada	DQ
	1	Danny McFarlane	Jamaica	DNF

First 2 of each semifinal (Q) qualified directly for the final.

Rank	Heat	Name	Nationality	Time	Notes
1	1	Paul McKee	Ireland	46.24	Q, NR
1	2	Daniel Caines	Great Britain	46.24	Q
3	2	Tyree Washington	United States	46.50	Q
4	2	David McCarthy	Ireland	46.61	Q, PB
5	1	Jamie Baulch	Great Britain	46.74	Q
6	1	Daniel Batman	Australia	46.76	Q
7	2	Marek Plawgo	Poland	46.82
8	1	Ioan Lucian Vieru	Romania	47.01
8	2	Cedric van Branteghem	Belgium	47.01
10	1	Chris Brown	Bahamas	47.03
11	1	Sofiane Labidi	Tunisia	47.14
12	2	David Canal	Spain	47.17