Objective: The influence of Ankaferd Blood Stopper (R) (ABS) was experimentally investigated on calvarial defects in rats. Material and Methods: Fourteen Wistar-albino rats equally divided into two groups, control group (G1) and drug group (G2), were included in the study. In G1, only right frontal craniectomy was performed. In G2, 0.5ml ABS was topically applied with a syringe after craniectomy. Surface areas of the defects were measured after four weeks, and comparative reconstruction images with were obtained, computed tomography (CT) as well. Blood samples were also collected to evaluate prothrombin time (PT), international normalized ratio (INR) and activated partial thromboplastin time (aPTT), and tissue samples were harvested for histologic examination. Results: Mean defect area in G1 (7.20 +/- 2.62 mm(2)) was significantly larger than that in G2 (1.83 +/- 1.65 mm(2)) (p<0.001). Mean PT, INR and aPTT values were not different between the two groups (p>0.05). Three dimensional (3D) CT analysis and histological examination revealed prominent osteogenesis in G2. Conclusion: We observed that surface area of the calvarial defects decreased significantly after ABS administration, and this observation was confirmed by 3D CT analysis and histology. Thus, ABS seems to have a potential of bone promoting effect; however, precise mechanisms underlying this osteogenetic activity still remain unexplained.