Platelet Rich Fibrin (PRF) is a new biological augmentation material which is remarkable with its rich cellular components and growth factors. The aim of this study was to evaluate the effect of PRF on tendon healing in a rat model. PRF and control groups included eight rats. PRF was obtained with centrifuging blood collected from the rats and applied on the tendon repair site in Achilles tendon injury model created in rats. Effectiveness of PRF was evaluated with histological and immuno-histochemical methods. PRF improves formation of regular collagen structures (P<0.01) and also increases vascularity (P<0.05) of the tendon repair site. Cartilage formation occurred both in PRF and control groups. Gap formation was observed only in the control group. PRF is an autogenous biomaterial which enhances and support tendon healing.