Athletics at the 1979 Pan American Games – Men's 400 metres

The men's 400 metres sprint competition of the athletics events at the 1979 Pan American Games took place at the Estadio Sixto Escobar. The defending Pan American Games champion was Ronnie Ray of the United States.

Records
Prior to this competition, the existing world and Pan American Games records were as follows:

Results
All times shown are in seconds.

Heats
Held on 11 July

Semifinals
Held on 11 July

Final
Held on 12 July