Reproductive and developmental toxicities of zinc supplementation in F 0 rats and F 1 progeny were examined. Rats were treated by gavaging with zinc chloride (ZnCl 2 ) at 0.0, 7.5, 15 and 30mg/kg-d. ZnCl 2 treatment was associated with deficient energy imbalances, reduced number of live pups/litter, decreased live birth index, increased mortality and increased fetal resorption. Changes in serum clinical chemistry and hematologic parameters were sex-related. In F 0 females, ZnCl 2 was associated with increased liver/body weight ratios, reduced creatinine and reduced alkaline phosphatase concentrations. In F 0 males, ZnCl 2 significantly increased relative liver weight and elevated γ-GGT. In addition, at birth, F 1 males exhibited, a significant (p<0.05) increase in anogenital distance, whereas ZnCl 2 hastened the time of eye opening and incisor eruption in males and females. These results indicate that excess ZnCl 2 supplementation before and during pregnancy and during lactation could pose some health risk concerns to pregnant mothers and their offspring.