A total of 64 patients of osteoarthritis of the knee joints were studied to observe the effects of isometric quadriceps muscle strengthening exercise plus non-steroidal anti-inflammatory drugs (NSAIDs) on osteoarthritis of knee joints. Another 75 patients were treated with NSAIDs as control. They were assessed by visual analogue scale, OMAC scale and range of motion of the knee joints and followed-up weekly for six weeks. Improvement was found in both groups (p= 0.001) after treatment. In comparison, more improvement was found in the exercise group after four weeks (p= 009). Then improvement was gradually increased day by day and finally there was highly significant improvement (p=0.001). This study suggests that isometric quadriceps muscle strengthening exercise has its beneficial role to reduce symptoms in osteoarthritis knee.