 Anorganic bovine bone mineral ABBM is extensively used in the treatment of intrabony defects. Platelet rich fibrin PRF is a new generation platelet concentrate with a simplified technique. Although there are some studies on the use of PRF in the treatment of intrabony defects, to date none of them evaluate its additive effects with ABBM. Therefore, a randomized, split mouth clinical trial was conducted to compare the healing of intrabony defects treated with a PRFABBM combination and to those obtained with ABBM alone. Using a split mouth design, 15 paired intrabony defects were randomly treated with either ABBM alone control group or with ABBM- PRF combination test group. The following clinical parameters and radiographic measurements were recorded at baseline and six months postoperatively: plaque index PI, gingival index GI, probing depth PD, gingival recession GR, clinical attachment level CAL, vertical bone loss, the depth of the defect and defect angle 