The effect of calcium and boron supplementation on bone strength was determined in growing and ovariectomized (OVX) Sparague-Dawley rats. Rats were divided into 9 groups and fed diet with different intake levels of calcium and boron for 4 weeks. About fifty percentages of rats in each group were OVX and the others were sham-operated. The rats were fed same diets after operation for 8 weeks. The feed intake, body weight gain, and FER were significantly higher in OVX rats than those in sham-operated ones. Serum osteocalcin, bone formation biomarker, was significantly increased with increment in calcium and boron intakes. Serum estradiol was lower in OVX rats than in sham-operated ones. Bone mineral density of femur was significantly lower in OVX rats than in other group. The breaking forces of bones were not significantly different among the groups. The urinary excretion of deoxypyridinoline, osteolytic marker was significantly increased with increment in calcium intake and ovariectomy. The urinary calcium excretion was significantly increased with increment in calcium intake, but decreased with increment in boron intake. According to theses results, the boron supplementation resulted in higher serum osteocalcin and lower urinary calcium excretion. Therefore, it could be suggested that the boron supplementation may be complementary and useful to calcium nutrition for bone health.