Early chondromalacia patellae is initiated by malalignment in the extensor machaniam and abno-rmal patellofemoral tracking. It is well known that chondromalacia often occurs in recurrent pateIlar subluxation. In the 50 normal and 60 pathologic knees, the following five parameters were studied; 1) Q angle 2) PT ratio by Insall & Salvati method 3) AB ratio dy Blackburne & Peel method 4) sulcus angle 5) congruence angle. The following conclusions were made. l. In 50 normal asymptomatic knees, the average Q angle was 14°. The patellar length was equal to the patellar ligament length and the average congruence angle was −8°. In 40 knees with “Chondromalacia”, the Q angle was increaed (19.5°), and the average congruence angle was −2°. 3. In 20 knees with recurrent subaxation, the patellar was high riding (PT ratio, 0.89), the sulcus angle was shallow (145.1°), and the average congruence angle was +4.35°.