PURPOSE: To investigate the effect of bone connecting powder on stimulation of bone healing, we performed a biomechenical study using the rats in double blinded method. MATERIALS AND METHODS: One hundred ten-week-old korean rats were used. We performed closed intramedullary nailing with #2 Kirschner wire on the right femur and then transverse fracture was created on the right femoral shaft. The rats were divided into two groups in double blind method, one group was bone connecting powder feeding group and the other was placebo group. The rats were euthenized four weeks after fracture. We measured the ultimate load, stiffness, ultimate stress by 3-point bending test using electromechanical testing machine. The code used for double blinded method was disclosed after biomechanical test. RESULT: Biomechenical test was performed at four weeks after fracture, in which there were 38 rats alive in the study group and 36 rats alive in the placebo group. There were 5 nonunion in study group, 7 in placebo group. The ultimate load was 40.77 ± 28.09N for study group, 32.39 ±25.10N for placebo group and stiffness was 49.98 ± 45.32N/mm, 40.52 ±36.61N/mm respectively. We calculated the ultimate stress to correct the difference from each bone's shape and thickness and it was 11.017 ± 10.170N/mm 2 , 6.659 ±6.670N/mm 2 for each other(p=0.041). CONCLUSION: On the basis of this biomechenical study, it may be concluded that fracture healing is stimulated by bone connecting powder.