Background: Platelet-rich plasma (PRP) and hyaluronic acid have been shown to be useful in the treatment of knee osteoarthritis. However, investigations comparing the efficacy of these two drugs together are insufficient. Aim of the Work: to perform a systematic review of comparative study between effect of platelet rich plasma and hyalouronic acid in treatment of osteoarthritis. Material and methods: This systematic review was performed according to PRIMSA guidelines using the Cochrane database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed and MEDLINE as database for search,from 2015 to 2019 .Results: A total of 230 potential studies were identified with the first search strategy. Of these, 82 studies were excluded according to the eligibility criteria. First, we identified 14 studies that satisfied the predefined inclusion criteria. Eventually,we concluded that only thirteen study is the most suitable to our review. three prospective studies and ten randomized trials were included in final quality assessment and data extraction Conclusion: PRP injections reduced pain more effectively than HA injections in OA of the knee at 6 and 12 months of follow-up evaluated by WOMAC pain score, while the VAS showed no significant difference at 3 and 6 months. Additionally, similar results were observed for the function recovery according to the WOMAC function score and EQ VAS. Due to the limited quality and data of the evidence currently available, more high-quality randomized controlled trials are required