2013 World Youth Championships in Athletics – Boys' 400 metres

The Boys' 400 metres at the 2013 World Youth Championships in Athletics was held on 10–12 July.

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

Heats
Qualification rule: first 2 of each heat (Q) plus the 8 fastest times (q) qualified.

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