2011 World Youth Championships in Athletics – Girls' 400 metres

The girls' 400 metres at the 2011 World Youth Championships in Athletics was held at the Stadium Nord Lille Métropole on 6 and 8 July.

Records
Prior to the competition, the following records were as follows.

No new records were set during the competition.

Heats
Qualification rule: first 3 of each heat (Q) plus the 6 fastest times (q) qualified.

Semifinal
Qualification rule: first 2 of each heat (Q) plus the 2 fastest times (q) qualified.