Aim: comparative evaluation of alloplastic bone graft alone and combination of autologous platelet rich fibrin with alloplastic bone graft in the treatment of vertical intrabony defects by selecting patients with chronic periodontitis. Methodology: A total 28 sites with vertical intrabony defects in chronic periodontitis patients of age range 25-54 years were included in the study. They were divided into group A-14 sites underwent open flap debridement with placement of bone graft alone and group B -14 sites underwent open flap debridement with placement of bone graft and PRF after a thorough phase1 therapy. Clinical evaluation of surgical sites were carried out using PPD, MGI, RAL, Mobility at baseline, 3 months and 6 months interval. Radiographic assessment of the defect was done at baseline 3 months and at 6 month interval. Results: The mean probing depth was 7.43 ± 0.852 in group A and 7.86 ± 0.770 in group B. At the end of 3rd month it was 5.43 ± 0.646 in group A and 4.43 ± 0.514 in group B. At the end of 6 months it was 4.14 ± 0.663 in group A and 3.36 ± 0.497 in group B. Relative attachment level was 11.36 ± 0.842 in group A and 11.07 ± 0.730 in group B. At the end of 3rd month it was 9.36 ± 0.842 in group A and 8.00 ± 0.877 in group B. At the end of 6 months it was 7.50 ± 0.650 in group A and 5.21 ± 1.051 in group B. In modified gingival index there is no significant difference at the end of 6 months between group A and group B. The mean mobility score in group A as well as in group B 78.6% had score 1, 21.4% had score 2 in baseline. In the 3rd month too, both the groups had 78.6%- score 1 and 21.4%- score 2. At the end of 6 months, in all the 14 sites mobility score was 1 in group A as well as in group B. In baseline radiographic evaluation mean value was 13.00 ± 1.75 in group A and 14.79 ± 2.72 in group B. At the end of 3rd month it was 7.00 ± 1.03 in group A and 6.36 ± 1.08 in group B. At the end of 6 months it was 6.05 ± 0.855 in group A and 5.57 ± 0.852 in group B. This shows that group B is better than group A. Conclusion: In comparative evaluation of open flap debridement with bone graft and open flap debridement in combination with bone graft and PRF in the treatment of intrabony defects there was significant improvement in clinical parameters like probing pocket depth and gain in clinical attachment level in test sites at 6 month interval. Radiographic evaluation showed some evidence of bone fill in both the groups, however significantly higher percentage of bone fill was observed in test sites.