The aim of the present study was to analyze the effects of platelet-rich fibrin (PRF) and bone marrow mononuclear cells (BMMC) on the bone regeneration process. Sixty Wistar rats were used on this experimental research. Half of the sample was sacrificed to obtain both experimental materials. In the others thirty were submitted to a two surgical calvaria bone defects. One of these defects was treated with the experimental materials. In another side of the parietal suture the defects were filled with the particulate autogenous bone graft. The sample was divided in: Group I – the experimental cavity was filled PRF. Group II – the cavity was treated with PRF + BMMC. Each group had fifteen rats and they were sacrificed in three moments: 7, 15 and 30 days. Histologic analysis: at seven days period, both experimental and control groups did not show bone formation. In the other two sacrificied periods (15 and 30 days) both experimental groups had not significantly diference ( P > 0.05). The histomorphometric analysis did not show significantly difference between experimental and control groups. The platelet-rich fibrin only or with the bone marrow mononuclear cells showed a bone regeneration similar to autogenous bone graft on the three sacrificied periods (7, 15 and 30 days).