Among the 4,020 athletes (males 73%, females 27%) treated at the Department of Sports Medicine of the Deaconess Institute, Oulu, Finland in the period 1986-1989 there were 273 athletes with 330 of instances Achilles tendon overuse. Peritendinitis, tendinitis, partial rupture, retrocalcanear bursitis and insertiotendinitis were the most common diagnoses. Acute and subacute ailments were usually treated successfully by conservative means. 45.5% of the overuse injuries became chronic, failed to respond to conservative treatment and were treated surgically. The results were excellent or good in 86% of those operated on for chronic peritendinitis. The overall results were good in 69.3% of the patients.