Swimming at the 1984 Summer Olympics – Men's 400 metre individual medley

The final of the men's 400 metre individual medley event at the 1984 Summer Olympics was held in the McDonald's Olympic Swim Stadium in Los Angeles, California, on July 30, 1984. 24 athletes participated in the heats, with the fastest eight qualifying for the final.

Records
Prior to this competition, the existing world and Olympic records were as follows.

The following records were established during the competition:

Heats
Rule: The eight fastest swimmers advance to final A (Q), while the next eight to final B (q).