The differences between male and female performance in free style swimming events are compared. It is found that the differences between male and female performance, as measured by world records, is declining in all events and declining most rapidly in those events in which the differences at the present time are largest. Analysis of national records for these events shows important differences between different countries in average male/female differentials.

A different set of physical and physiological constraints operate on swimming compared to track performance, but they would seem to be less important in influencing male/female differences. Social factors also seem to be less important in swimming than in track athletics in perpetuating performance differences but are nevertheless still operative.