Abstract :Osteoarthritis (OA) is the most common type of arthritis and the major cause of chronic musculoskeletal mobility disability in the elderly populations worldwide. In this study, scaffold free autogenous platelet rich plasma (PRP) was used in an experimental animal model of OA by direct intra articular injection. 15 white New Zealand adult rabbits of both sexes were used in this study. OA was induced by anterior cruciate ligament transection of the knee joints. Immediately following operation, a single dose of (0.5 ml) platelet rich plasma (PRP) was delivered to the injured knee by direct intra articular injection in the test groups. The control group received no PRP injection. The knees were examined after four and eightweeks following the operation histopathologically. Pathologic assessment confirmed development of OA changes after8 weeks in the control group. Rabbits which received PRP showed lower degree of cartilage degeneration, osteophyte formation, and subchondral sclerosis than the control group at 8 weeks after surgery. In conclusion, PRP could be a valuable medium and a promising source for the prevention of the development of OA.