The treatment of anterior cruciate ligament (ACL) rupture continues to be a controversial subject. This study was undertaken to compare long-term results of different therapy regimens A total of 52 patients (mean age: 34.7 +/- 3.2 years) who underwent ACL reconstruction using the central one third of the patellar tendon and 32 patients (mean age: 38.3 +/- 5.2 years) treated conservatively were evaluated 5-7 years clinically, radiologically and with respect to their sports activities. In all, 25% of the patients operated on subjectively rated their knees as "excellent", 40.4% as "very good", 22.2% "good", 12.5% "fair" and 0% as "poor". The ratings for the conservatively treated group were: 12.9%, 19.4%, 29%, 25.8% and 12.5%, respectively. The results of the OAK score were significantly better for the surgically treated group (87.5 +/- 7.1 points compared with 77.1 +/- 13.4). An increasing number of degenerative changes were found on radiographs in both groups at follow-up as compared with their pre-injury status.