During the period 1987-91, 153 cases of total Achilles tendon rupture were diagnosed in the city of Malmo (population 230,000). Almost two thirds were caused by sporting activities, notably badminton. Ruptures caused by nonsports injuries were found in older subjects. Compared to the age-specific incidence in 1950-73, a marked increase in both sports and nonsports injuries was found and patients in the latter group were older than in the former period. Patients with Achilles tendon ruptures can be classified into two subgroups with partly different etiologies: young or middle-aged athletes and older non-athletic persons. The increase in the former group is mostly explained by increased participation in recreational sports; the cause of increase in the latter group is unknown.