The weight bearing views are used as means to evaluate the articular status of the medial and lateral cartilages of the joint. Weight bearing view should reflect the relationships of the tibiofemoral aligment as well as demonstrating the loss of articular catilage more reliably than x-ray without weight bearing. However the conventional weight bearing views obtained with knee in extension, may not fully reflect the extent of articular cartilage loss. A flexion weight bearing view of the knee obtained at 30° to 40° of the joint flexion may be more sensitive in asessing damages to hyaline cartilage beacause the knee flexion is an important component of the stance phase. Kettelkamp et al (1973) revealed that the forces generated across the knee range from 2 to 4 times the body weight during stance phase and are greatest during heel strike and toe off when the knee is flexed. At the toe off, the knee is in nearly 30° flexion. With the flexion, the contact area migrates posteriorly within the joint and becomes smaIler with knee flexion which is in turn leading to degenerative changes. It is based on above fact that flexion weight bearing views are more sensitive in assessing the damages in articular cartilages in degenerative arthritis. We have reviewed weight bearing x-ray of 180 symptomatic knees (in 150 paients) who are over 40 years old, with more than 6 months history of knee pains. The results of flexion and extension weight bearing views were analyzed and compared with each other. The results were as follows; 1. The ages were ranged from 40 to 88 years old, The mean age was 57.2 year. Female to male ratio was 5 to l. 2. Among 180 knees, 158 showed no cartilage space narrowing in weight bearing views in full extension, however 60 (37.9%) of these 158 knees did show the cartilage space narrowing on the flexion weight bearing views. 3. Of the 22 knees that showed cartilage space narrowing in extension views, all had demonstrated narrowing in flexion views. But 17 (77.3%) of these 22 had demonstrated additional cartilage space narrowing of 2mm or more on the flexion weight bearing views. 4. In reviewing the weight bearing x-rays of 180 degenerative knees, the weight bearing views with knee in flexion had revealed the significant additional narrowing in 77 of 180 knees (43.0%). In early detection of degenerative arthritis of the knee, the weight bearing view in 40° flexion is more significant and sensitive in demonstrating the loss of articular cartilage of the knee joint.