During the years 1980-1989, 450 patients with an acute anterior cruciate ligament (ACL) rupture were treated at the University Hospital of Tampere, Finland. ACL ruptures were diagnosed by arthroscopy or open surgery. The data were analyzed in terms of patient age, sex, injury etiology, injury type and sports activity to determine the trends in the 1980s. The number of ACL tears seen in the Hospital increased by 247% over this period. Sixty-three percent of the patients were male (mean age 33 years) and 37% female (mean age 39 years), and there were no changes in the sex and age distribution in 1980s. The most common injury type was the isolated ACL rupture (51%), followed by a combination injury of the ACL and medial collateral ligament (38%). Isolated ACL ruptures in the 1980s increased 6.5 times. Sports accounted for 54% of all injuries without any sign of change in their relative proportion in 1980s. The most common sports causing the rupture were soccer (29%), downhill skiing (20%), cross-country skiing (12%) and volleyball (12%). From 1980 to 1989, there was a decrease (2 times) in ACL injuries sustained in cross-country skiing and a substantial (30 times) increase in ACL injuries sustained in downhill skiing.