Clinically the problems of patello-femoral joint are easily overlooked. The diagnosis of dislocation or subluxation of the patella is difficult, because the dislocated or subluxated patella can be reduced spontaneously. For the treatment of patellar dislocation or subluxation more than 100 operative methods have been reported, and thus it is difficult to choose an appropriate one. There have been reported a variety postoperative complications including recurrent dislocation and degenerative arthritis. From 1984 to 1991, 10 knees in 10 patients who had patellar dislocation were surgically treated at Kyung Hee University Hospital. The patient's age at surgery averaged 22 years, ranging from 8 to 44 years old. The ratio of female to male was 8 to 2. There were 6 recurrent dislacation and 4 habitual dislocation of the knee. 4 of 6 patients with recurrent dislocation had history of trauma and intermittent dislocation. In 4 patients with habitual dislocation (2 were congenital), patella dislocated definitely beyond 30°-70° in flexion the knee. Definite subluxation or tilt of the patella was found in 5 of 10 kness. Loose bodies were confirmed radiologically in 3 knees. Methods of surgical treatment included: 1) release of lateral retinaculum alone in 2 knees, 2) release of lateral retinaculum and proximal realingnment of the extensor mechanism in 2 knees, and 3) release of lateral retinaculum and proximal and distal realignment of the extensor mechanism in 6 knees. At an average follow-up period of 4 years and 2 months (range, from 1 year and 4 months to 8 years), according to the Crosby and Insalls classification, 7 kness were rated either excellent or good, whereas 2 knees were rated worse (symptoms of recurrent dislocation and radiological finding of subluxation).