The prevalence of radiographic signs of gonarthrosis and its relation to knee injuries were studied in 286 former soccer players--215 nonelite and 71 elite players--and were compared with 572 age-matched controls with a mean age of 55 years. The prevalence of gonarthrosis among the nonelite players was 4.2%, among the elite players 15.5%, and among the controls 1.6%. Seven of the soccer players had known anterior cruciate ligament injuries, and 40 had had meniscectomies. Of the 32 nonelite players with knee injuries, 4 (13%) had gonarthrosis, and of the 183 without known knee injuries 5 (3%) had gonarthrosis. Among the elite players, the prevalence of gonarthrosis in knees without diagnosed injuries was 11%. We conclude that soccer, especially at an advanced level, is associated with an increased risk for gonarthrosis. After excluding subjects with known knee injuries, there was no difference between nonelite players and controls, but we found a higher rate of gonarthrosis among the elite players.