Objective. The aim of this study is to evaluate the efficacy of platelet-rich plasma (PRP) clinically and radiographically when combined with bovine derived hydroxyapatite (HA) bone grafting materials and resorbable collagen membranes for the treatment of intra-bony defects frequently seen at the distal aspect of mandibular second molars following the surgical extraction of fully impacted mandibular wisdom teeth. Study design. Eighteen patients were scheduled for post-operative visits at 1, 3 and 6 months post-operatively, probing depths were measured and digital panoramic radiographs were taken. Results. There were no significant differences on probing depths among two groups. Radiographic assessment also showed no significant difference among groups at 1st and 6th month intervals, while 3 months post-operatively the amount of radiographic density at the PRP side was significantly higher. Conclusion. Combined use of PRP and bovine-derived HA graft materials for the treatment of intra-bony defects might be an appropriate approach when the main goal is providing earlier bone regeneration.