In normal weanling male rats, the intraperitoneal administration of zinc sulphate (ZnSO4) resulted in a decreased hepatic and an increased plasa concentration of vitamin A after 2 h. In an in vitro study, the vitamin A concentrations of liver homogenates were markedly increased when homogenized livers were treated with ZnSO4, ZnSO4, however, did not show any effect on plasma and liver concentrations of vitamin E. These results indicate that zinc may be specifically involved in mobilizing vitamin A from liver to the circulation of normal animals within a short period. The trace element, therefore, could be used only to treat cases of depressed vitamin A in plasma but also to treat hepatic toxicity from hypervitaminosis A.