Influences of u-tocopherol on the toxicity of vitamin A acetate in male rats were studied. The obtained results are as follows; 1) The administration of vitamin A acetate 500,000 IU/Kg i.p. twice at 3 days interval decreased the liver weight/body weight and increased the spleen weight/body weight, and increased activities of SGOT and alkaline phosphatase, and also increased BUN and creatinine. 2) ${alpha}$-Tocopherol administered together with vitamin A acetate as given as the above 1) poteniated the increase of SGOT activity caused by vitamin A acetate and reduced the increase of alkaline phosphatase activity and creatinine which were caused by vitamin A acetate. 3) The administration of vitamin A acetate 500,000 IU/Kg i.p. twice a week for 4 weeks showed remarkable decrease of body weight gain and the effect of it was larger in later stage than in early. It increased significantly liver weight/body weight and further increased the activities of SGOT, SGPT and alkaline phosphatase, and showed no influnence on BUN and creatinine. 4) ${alpha}$-Tocopherol administered together with vitamin A acetate as given as the above 3) reduced the decrease of body weight gain caused by vitamin A acetate, and potentiated remarkably the increased activities of SGOT and alkaline phosphatase which were caused by vitamin A acetate.