Objectives: The present study aimed to assess the effect of hydroxyapatite and hydroxyapatite combined with platelet-rich plasma graft in treatment of intrabony periodontal defects. Subjects and Methods: The present study was conducted on twenty-four patients with advanced chronic periodontitis, having clinically similar interproximal advanced osseous lesions coming to the outpatient clinic of the Faculty of Dentistry, Suez Canal University. Following initial phase of periodontal therapy and re-evaluation, patients were classified randomly into two equal groups: Group I: Consisted of 12 patients, were treated with full thickness mucoperiosteal flap surgical technique and Hydroxyapatite bone graft. Group II: Consisted of 12 patients, were treated with full thickness mucoperiosteal flap surgical technique and Hydroxyapatite bone graft combined with platelet-rich plasma graft. Results: The intragroup comparison of each of hydroxyapatite bone graft and hydroxyapatite bone graft with platelet-rich plasma group showed statistically significant decrease in pocket depth, clinical attachment level, plaque index, gingival index and bone density from baseline, 3 months and 6 months, while the intergroup comparison showed no statistical significant difference. Conclusion: hydroxyapatite bone graft and hydroxyapatite bone graft combined with platelet-rich plasma led to improvement of clinical and radiographic parameters over the course of the study.