Swimming at the 2013 World Aquatics Championships – Men's 4 × 100 metre medley relay

The men's 4 × 100 metre medley relay event in swimming at the 2013 World Aquatics Championships took place on 4 August at the Palau Sant Jordi in Barcelona, Spain.

Records
Prior to this competition, the existing world and championship records were:

Heats
The heats were held at 10:51.

Final
The final was held at 19:31.