OBJECTIVES: We have studied the effects of Yuhan bone connecting powder on the healing process of the frauture at the osteotomized bones in rat, using bone densitometer, X-ray and morphological studies after administration of Yuhan bone connecting powder which has been reported in China as enhancing the processes of the fracture healing. MATERIALS AND METHODS: 90 Sprague-Dawley male rats were divided into the rib and tibia osteotomy groups. Each group was subdivided into the control, low dosage and high dosage groups. Rib and tibia were osteotomized under the general anesthesia with ketamin. From the next day after operation, Yuhan bone connecting powder diluted with distilled water was administrated to low(0.68g/kg) and high(1.36g/kg) dosage groups per se. Same amount of the distilled water was used to the control group. 1.5cm long rib including the osteotomy site and whole tibia were excised. Bone densitometer using dual energy X-ray absorptiometry, radiological and morphological studies with HE stain and alcian blue(pH 2.5)-PAS stain were performed. RESULTS: BMD showed statistically significant difference between control group, low dose group and high dose group at 2weeks after treatment(p=0.035), but did not show such a good result at 1week(p=ns) and 4weeks(p=0.091) after treatment. Radiologically, after treatment for 2 weeks, the low and high dose groups showed more active callus formation than control group. Morphologically, dilated numerous blood vessels adjacent the bony trabeculae and well developed cartilagenous callus were observed in the experimental group at the 1st week. At the 2nd week, many newly formed bony trabeculae were formed from the cartilagenous callus, and at the 4th week relatively thick compact bone and bony trabeculae were connecting the both osteotomy ends. CONCLUSION: BMD at the osteotomy site seemed to be increased after administration with Yuhan bone connecting powder to rats, and this finding was supported radiologically at 2weeks after treatment. Morphologically, at the early stage of the fracture healing, numerous dilated blood vessels were distributed and many bony trabeculae were formed from the cartilagenous callus. At the remodelling stage relatively thick compact bone was connecting the both ends of the osteotomy site. So it is suggested that Yuhan bone connecting powder would induce enhancing the healing process of the osteotomized bone in rat through active vascularization, mineralization of the cartilage matrix, endochondral ossification and remodelling.