To study the effect of cadmium exposure on maternal and fetal zinc metabolism, rats were exposed to 0, 5, 50, or 100 ppm Cd in the drinking water on Days 6 through 20 of pregnancy. In comparison to controls, fetal and maternal weights were slightly reduced in the 50- and 100-ppm groups, but not the 5-ppm group. Multiple regression analysis revealed that in the 50-ppm group, but not in the 100-ppm group, the decrease in fetal weight was not solely a consequence of decreased maternal weight. Cd accumulated in a dose-dependent manner in both maternal organs and fetuses, although the absolute concentrations in fetuses were very low as compared to those of maternal tissues. In the 50- and 100-ppm groups, zinc concentrations were significantly increased in maternal liver and kidney, and significantly decreased in fetal liver. The changes in tissue Zn concentrations were accompanied by altered Zn-metalloenzyme activities in both maternal and fetal tissues. These findings support the hypothesis that Cd-induced maternal zinc retention is responsible for fetal Zn deprivation and impaired fetal growth.