The present study was undertaken in an effort to investigate the effects of alcohol on survival of mice and on their humoral and cellular immune responses. The immune responses examined were Arthus and delayed-type hyperrsnesitivity(DTH) reactions to sheep red blood cells (SRBC), contact hyp-ersensitivity to dinitrofluorobenzend(DMFB), antibody response to thymus-dependent SRBC and to thymus-independent polyvinylpyrroridone(PVP), and the recovery of Cryptococcus neoformans from the liver, spleen, kidney and brain of experimentally infected mice. The administration of ethanol concentrations of 20% or less did not cause any change in survival rates as compared withs saline injected control group. In general, ethanol administration inhibited the Arthus and DTH reactions to SRBC, contact hypersensitivity to DNFB, and antibody response to both SRBC and PVP and it also decreased the resistance of mice to C. neoformans infection. Taken together, the present study stongly suggested that ethanol inhibits immune response and decreaes the resistance of mice to C. neoformans infections.