1. The degenerative changes of the articular surface of the fabella have been designated chondromalacia fabellae. 2. Localized tenderness and pain on passive motion of the fabella appear to be the chief diagnostic criteria. 3. Cure consists in the removal of the involved fabella. 4. At operation that portion of the posterior articular surface of the lateral femoral condyle which is in intimate contact with the fabella should be carefully inspected for evidence of degenerative changes. If such changes are present, this portion of the condyle should be removed. 5. It is hoped that increased experience with chondromalacia fabellae will help to reduce the percentage of error in the diagnosis of lesions of the knee joint.