Platelet gel (PG) includes concentrated dose of growth factors which plays role in physiological processes of healing. The goal of this study is to evaluate repairing effects of intra-articular injection of PG use in a rat model of knee osteoarthritis (OA). A total of 20 rats were randomly distributed into a PG group and a control group. Both the groups were induced OA in knee joints with intra-articular formaline injection. The rats in the PG group and the control group were injected in the knee joint with PG and 0.9% NaCl solution, respectively. Two weeks after last injections, all rats were sacrificed by ether asphyxiation. Tissue samples were obtained from the knee joints and were examined histopathologically. No statistically significant differences were found between the groups regarding cartilage healing (P > .05). We were unable to determine any beneficial or harmful effects of PG on joint cartilage healing in OA.