Purpose: Platelet rich fibrin (PRF) has been widely and successfully used in periodontal regeneration. Injectable PRF (i PRF) is a liquid form of PRF containing more leucocyte and growth factors. I-PRF was used with great success in management of gingival recession and implant therapy. So the aim of the study was to evaluate the benefit of adding i-PRF to xenograft in management of periodontal intraosseous defects. Subjects and Methods: Twenty four patients (age range 36 - 59 years), with stage III periodontitis with at least one intrabony defect, probing pocket depth > 5 mm and radiographic evidence of vertical bone loss, were enrolled in the present study. The patients were equally divided into two groups, the test group (i-PRF and xenograft) and the control group (xenograft only). Probing depth (PD), clinical attachment level (CAL.), bone defect depth and bone density were recorded at baseline and after 6 months. Results: The results showed a statistical significant reduction in PD, gain in CAL, bone fill and change in bone density from preoperative to 6 months in each group separately. There was a statistical significant difference between test and control groups with mean and standard deviation (SD) of PD reduction (4.2±0.4; 3.3±0.7) and CAL gain (3.8±0.4 ; 2.9±0.8) respectively in favor of the test group. Regarding bone fill, there was no statistical significant difference between both groups with mean and SD (2.6±0.7; 2±0.8) respectively. As for the increase in bone density, there was a statistical significant difference between both groups with mean and SD (17.5±4.9 ;10.9±6.8) respectively. Conclusion: We can conclude that adding i-PRF to bone grafting material might have a beneficial impact in treatment of periodontal intraosseous defects.