1999 Pan Pacific Swimming Championships – Men's 400 metre individual medley

The men's 400 metre individual medley competition at the 1999 Pan Pacific Swimming Championships took place on August 23 at the Sydney International Aquatic Centre. The last champion was Matthew Dunn of Australia.

This race consisted of eight lengths of the pool. The first two lengths were swum using the butterfly stroke, the second pair with the backstroke, the third pair of lengths in breaststroke, and the final two were freestyle.

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

Results
All times are in minutes and seconds.

Heats
The first round was held on August 23.

Final
The final was held on August 23.