Background: Osteoarthritis (OA) is the most common type of arthritis. It is a degenerative joint disease. OA is usually defined according to radiographic changes. Conventional radiographs (CR) were considered the most relevant outcome measure to assess the progression of OA in clinical trials and epidemiological studies. Many modalities are used in treatment of knee OA. There is a distinct need for new procedures that are cost effective by reducing the need for pharmaceutical and surgical management, while targeting the biochemical process of OA. Platelet-rich plasma (PRP) is one of these new procedures. PRP was found to increase hyaluronic acid (HA) concentration, stabilizing angiogenesis in patients with osteoarthritic knees.    Aim of the study: Was to assess the value of intra articular injection of autologous platelet rich plasma in management of knee osteoarthritis.    Patients and methods: This study was conducted on 40 patients with primary knee osteoarthritis, divided into 2 groups; study group treated with 3 injections of PRP, and control group treated with single dosed high-molecular weight HA. Clinical assessment and visual analogue scale (VAS) scoring were done pretreatment and 3 months post treatment.    Results: Clinical improvement and reduction of VAS in both groups which is significant at the study group. Conclusion: PRP injection could be considered as a simple, safe, effective and non-palliative treatment that may promote cartilage healing in knee osteoarthritis as it improve the clinical condition and the function of the joint. Hence, it may represent a useful addition to the available therapeutic options for knee osteoarthritis.