Swimming at the 1971 Pan American Games – Men's 100 metre butterfly

The men's 100 metre butterfly competition of the swimming events at the 1971 Pan American Games took place on 10 August. The last Pan American Games champion was Mark Spitz of US.

This race consisted of two lengths of the pool, all in butterfly.

Results
All times are in minutes and seconds.

Final
The final was held on August 10.