Swimming at the 1988 Summer Olympics – Men's 400 metre individual medley

The men's 400 metre individual medley event at the 1988 Summer Olympics took place between 20–21 September at the Jamsil Indoor Swimming Pool in Seoul, South Korea.

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).