Sixty-eight knees in 62 patients wiht degenerative changes of the patellar joint surface, chondromalacia or arthrosis, were operated on with anterior displacement of the tibial tuberosity. Complications were encountered in no less than 22 joints and the results appeared to be somewhat related to these complications, particularly in women, even if a direct relationship between complications and remaining symptoms could not be demonstated. In a follow-up examination an average of 13 months after operation, approximately 90 per cent of the patients had improved, men as well as women. In an additional follow-up up, 30 months after operation, the men had maintained or even somewhat improved their good results whereas in women only about 70 per cent could not be classified as improved or free from symptoms. When those patients, who were not as regards all variables improved by surgery, were analysed separately, there was in this group a preponderance of women and particularly older women. Also, the patients with complications belonged to this group. Modifications of the surgical procedure did not seem to change the results nor were the results different in those patients in whom a superficial shaving of the articular cartilage of the patella had been added. The conclusion of the study is that anterior displacement of the tibial tuberosity has a lasting beneficial effect on patiens with degenerative changes of the patello-femoral joint.