| September 2 (preliminaries), September 4 (finals)|
The women's 100 metre butterfly competition of the swimming events at the 1959 Pan American Games took place on 2 September (preliminaries) and 4 September (finals). The last Pan American Games champion was Beth Whittall of Canada.
This race consisted of two lengths of the pool, all in butterfly.
Swimming at the 1959 Pan American Games – Women's 100 metre butterfly Wikipedia
All times are in minutes and seconds.
The first round was held on September 2.
The final was held on September 4.