Purpose: the aim of this study was to evaluate the efficiency of intra-articular injection of injectable platelet rich fibrin (i-PRF) in TMJ disc displacement with reduction. Materials and Methods:Thirty patients suffered from temporomandibular joint internal derangement (TMJID) were included in the study 1.5 ml i-PRF into the TMJ. The patients were clinically evaluated preoperatively and postoperatively at the intervals of 1week, 3, and 6 months. RESULTS:The differences between preoperative and postoperative status in all the measured parameters were statistically significant throughout the postoperative period. CONCLUSION: i-PRF injection is a safe and effective method in the treatment of TMJID.