Objectives: Treatment of bone defect still considered as a big challenge facing maxilo-facial surgery. Causes of bone defects are various e.g. acute trauma, congenital abnormalities, on­cological tissue resection, and progressive deforming diseases.New functional bone regeneration is one of the aims of bone tissue engineering through the synergistic collection of biomaterials, cells, and growth factors. Using tissue engineering to treat bone defect is apparent as a superior approach because the repair progression it is done by patient's own tissue by the time the regeneration is complete. Methods:Forty five adult male rats were selected for this study. They were divided into three groups, Group I (control –ve)rats were subjected to surgery for preparation of bony defect and left to heal normally, Group II (control +ve) Bone defect was filled with PRF membrane and Group III. Bone defect filled with PRF membrane seeded with BMSCs .Five rats from each group were sacrificed after 1 week, 2 weeks and 4 weeks weekly; the mandible was dissected, decalcified and prepared for(H & E) stain, Masson's Tri-chrome staining. Results:Bone cavity in group III showed more trabecular formation and organization of osteons than group I&II. Collagen fibers formation was more rapid in group III than other groups. Group I&II showed more inflammatory response than group III. Conclusions: PRF membrane seeded with BMSCs can regenerate bone effectively in a short Period.