Patellar pain must be separated from other causes of internal derangement of the knee by a careful history and precise examination followed by appropriate investigations. Once the cause of the pain is determined, malalignment or malposition of the patella must be sought. The Merchant view of the patellar femoral joint is recommended in this regard to demonstrate patellar incongruence. The malalignment syndrome may or may not show the pathologic changes described as "chondromalacia" and respond particularly well after proximal patellar realignment. In the remaining cases, pain may be caused by overuse, trauma, the odd-facet syndrome, an abnormal femoral ridge, or degenerative arthritis. This group of cases should be managed conservatively if possible because the results of surgical treatment are often disappointing. In selected cases some improvement may occur after excision of abnormal cartilage, tibial tubercle elevation, patellar replacement, or patellectomy.