Purpose: This clinical study was performed to evaluate the clinical effect of Platelet Rich Fibrin (PRF) application on healing process of periapical bony defects after endodontic peri-radicular microsurgery. Material and methods: Twenty-eight teeth in 25 patients were included in this study. They were divided into 2 equal groups, each including fourteen teeth. After retrograde filling was completed, the bony crypt was grafted with Platelet Rich Fibrin in the study group (Group A, n=14) and no graft in the control group (Group B, n=14). Patients were recalled at 12 months postoperatively for examination. Results: After one year of clinical and radiographic follow up, Group A showed higher success rate (81.8%), While Group B showed the lower success rate (45.4%). Significant difference in results was found between the two groups (P < 0.05). Conclusions: Within the limitation of this study, application of PRF in bony crypt after endodontic peri-radicular microsurgery showed higher long-term success rate and hence it may be considered as an adjunct autologous material to endodontic peri-radicular microsurgery.