Water influences skin inflammation of the external auditory canal. The common term for this illness is "swimmer's ear". Contributory factors are length of exposure to water, type of water and water pollution. The aim of the study was to compare risks for contracting the disease between patients with different exposure to swimming pool water. A retrospective case-control analysis of patients at the ENT-clinic was performed. Swimmers and water polo players swam in a swimming pool chlorinated by an automatic swimming pool cleaning system. Water sport players had a higher risk for ear skin inflammation than football players. Senior football players compared with players younger than 13 were not at increased risk. Swimmers and water polo players older than 13 were at higher risk. Swimmers were at higher risk than football players as well as water polo players. There was no difference for the risk of otitis externa between swimmers and water polo players. Swimmers and water polo players compared with other patients of the ENT-clinic were at higher risk than football players. Frequent and longer exposure to water has been proved to increase the risk of external auditory canal inflammation.