A series of surgically treated patellar tendon lesions among athletes is presented. The material was collected during 5 years from three sports injury clinics and from two hospitals. During this period the authors treated about 150 cases of jumper's knee, of which 34 cases were treated by operation. The athletes were mostly volley ball players, jumpers or runners. The operation revealed a necrotic focus of the patellar tendon in 21 cases, the retinaculum was thick and adherent in 16 patients and an exostosis of the patellar insertion was seen in two cases. The necrotic areas were excised, the thick and adherent retinaculum was divided and the exostoses were excised and drilled. Surgical treatment of chronic patellar tendon pains may give good results in selected cases.