Swimming at the 2015 World Aquatics Championships was held between 2 and 9 August 2015 in Kazan, Russia. The United States won the overall medal count, led by Katie Ledecky who claimed five gold medals.

The 16th FINA World Championships, also Aquatics 2015, were held in Kazan, Russia from 24 July to 9 August 2015. Russia hosted this event for the first time. The number of participating national teams (190), athletes (2,400) and the number of medals (75) were the most ever amongst these championships. This was the first time the World Aquatics Championships partially overlaps with the FINA World Masters Championships that have a number of athletes, countries (110) and medals (635) which are the most ever also.