Water was separated from water/ethanol mixtures by pervaporation using NaA and NaY zeolite membranes synthesized in our laboratory. The effects of a concentration of ethanol at the feed side and temperature were studied on the permeation flux and the separation factor of water with respect to ethanol. The separation factor obtained with the NaA zeolite membrane was found to be 1,000 times larger than that obtained with the NaY zeolite membrane. However, the water flux through the NaA zeolite membrane was observed to be lower by 1/2 through the NaY zeolite membrane. The water flux significantly increased as the temperature increased for both the NaA and the NaY zeolite membranes. The ethanol flux was not much changed through the NaA zeolite membrane below 0.8 mole fraction of ethanol in the feed solution as the temperature increased. On the other hand, the ethanol flux through the NaY zeolite membrane rapidly increased even below 0.8 mole fraction of ethanol as temperature increased.