Captafol (1H-Isoindole-1.3(2H)-dione, 3a, 4, 7, 7a-tetrahydro-2-[1, 1, 2, 2-tetrahydroethyltkio]) is widely used as fungicide in agriculture. Immune modulatory effects of captafol and ethanol were studied in mice. Mice administered captafol intra peritoneally every other day for 5 times, and ethanol per os as captafol. Mice were sensitized and challenged with sheep red blood cells, serum antibody titer, foot pad swelling, and rosette forming cell number were mediated immune response. 1. The result show that humoral immune response and cell mediatea response were suppressed by captafol. 2. Especially effect of ethanol on the captafol immune response were significantly suppressed the humoral immune response and cell mediated immune response.