The effect of beta-alanyl-L-histidinato zinc (AHZ), in which zinc is chelated to beta-alanyl-L-histidine, on bone metabolism was investigated in the femoral diaphysis of ovariectomized rats. AHZ (10, 30 and 100 mg/kg body weight/day) was orally administered to ovariectomized rats for 3 months. Ovariectomy significantly decreased the estradiol concentration in the serum as compared with that from sham-operated rats. This decrease was not altered by the dose of AHZ. The bone volume and dry weight in the femur of ovariectomized rats significantly decreased in comparison with those from sham-operated rats. Moreover, alkaline phosphatase activity, deoxyribonucleic acid (DNA) and calcium contents in the femoral diaphysis were significantly decreased by ovariectomy. The decreases of the femoral volume and dry weight, the femoral-diaphyseal alkaline phosphatase activity, DNA and calcium contents by ovariectomy were completely prevented by the tested doses of AHZ (10, 30 and 100 mg/kg/day). AHZ in the dose range of 10-100 mg/kg/day caused a significant increase in zinc content in the femoral diaphysis of ovariectomized rats. The present study suggests that the prolonged administration of AHZ can prevent bone loss by ovariectomy.