Purpose: To investigate the effect of rhBMP-2 on the healing of bone defect in the low calcium diet rat. Materials and Methods: To prepare the experimental model, control group was fed a normal diet and experimental group was fed a low calcium diet for 3 weeks. And then, 4 mm bicortical perforated bone defect was made on mandibular body of each rats. Experimental group was subdivided into two groups; experimental group 1 (rats given a low calcium diet before and after bone defect) and experimental group 2 (rats given a low calcium diet before and after bone defect with rhBMP-2 application). At 1, 3, 5 and 7 weeks after bone defect formation, the rats were terminated. The healing of bone defect was assessed by three-dimensional computerized tomography, soft x-ray radiography, and histopathological examination. Results : The wound healing of the bone defect for control group, experimental group 1, and experimental group 2 showed a increase from 3 weeks after bone defect formation. The experimental group 2 showed a more increase in healing amount than control group and experimental group 1 from 5 weeks after bone defect formation and the experimental group 2 showed a complete recovery of bone defect at 7 weeks after bone defect formation. Conclusion: The healing process of bone defect is accelerated by rhBMP-2 application in the low calcium diet rats.