This study was conducted to evaluate the efficacy of intra-articular injection of hyaluronic acid for the treatment of knee osteoarthritis. Patients with knee osteoarthritis were followed for a period of six months to assess the efficacy of intra-articular injection of hyaluronic acid given three times in three consecutive weeks. Fifty patients were reviewed at two, eight and 24 weeks post-injection. The average age was 60.9 years and female to male ratio was 3:1. Patients were assessed using the Lequesne Algofunctional Index for function, and the visual analogue score for pain and side effects. We found that the knee pain reduced and the function improved in most patients and these beneficial effects maintained for till the last follow up. The only side effect noted was one case of acute non-septic joint effusion after the 3rd injection. We concluded that intra-articular injection of hyaluronic acid can produce pain relief and functional improvement for up to 6 months.