The purpose of this study was to investigate differences of Ca, Mg and Zn utilization in young and adult rats fed standard diet for 3 weeks. Feed intake and body weight gain in young rats were significantly higher than in adult. There were no significant differences in serum levels of Ca and Zn across age and sex. In liver of young or male groups, Ca and Zn contents were significantly higher than in adult or female. There were no significant differences in tibia contents of Ca and Mg, but Zn content was increased when young or female groups was compared with the other groups. In mineral balances, daily intakes and retentions of Ca, Mg and Zn in young or male groups were significantly higher than those in adult or female. According to this results, it could be suggested that in growth period must be increased dietary intake of Ca, Mg and Zn to compromise the requirement for growth.