The effect of vitamin A on experimental hepatic fibrosis in rats induced by administration of carbon tetrachloride (CCl4) and pig serum was studied. Vitamin A content in the CCl4-induced cirrhotic liver decreased significantly. Administration of pig serum caused hepatic fibrosis without hepatocytic damage. Vitamin A suppressed induction of experimental hepatic fibrosis by CCl4 and pig serum. Neither hepatocytic injury nor increased activities of serum aspartate aminotransferase and glutamic pyruvic transaminase induced by CCl4 was diminished by vitamin A. These data provide evidence that vitamin A inhibits hepatic fibrogenesis and that this effect may be mediated by an action on stellate cells rather than hepatocytes.