Purpose: This experimental study was to evaluate and compare bone regeneration capacity of experimental bone defects filled with different autologous platelet concentrates (APCs) as a bone graft material in the rabbit's tibiae. Material and methods: A total of forty-two adult rabbits were included in this study. After creation of bone defects, the animals were randomly assigned to three groups. In control group, no bone graft was used (Group A, n=14), in one test group Plasma Rich in Growth Factors (PRGF) was used as bone graft material (Group B, n=14), and in the other test group Injectable Platelet Rich Fibrin (i-PRF) was used as bone graft material (Group C, n=14). After implantation, each group was further divided into two subgroups, where rabbits were sacrificed 2 and 4 weeks postoperatively and the defects were evaluated with histologic and histomorphometric analysis. Results: Both test groups (Group B and Group C) treated with APCs (PRGF: 10.92±0.85 & 41.53±2.55and i-PRF: 13.13±0.68 &57.27±1.66 at 2 and 4 weeks respectively) demonstrated higher percentages of new bone formation than the control group (5.11±1.15 & 30.31±1.29 at 2 and 4 weeks respectively) (P < 0.001). Significant difference was found between the two test groups and control group (P < 0.001). On the other hand, significant difference was found between test groups (P < 0.001). Conclusions: Within the limitation of this animal study, the adjunct implication of either i-PRF or PRGF in endodontic surgery may be of great significance as it dramatically improves bone regeneration.