Pervaporation with water-ethanol mixtures was carried out for three types of latex membranes, P(AN-BuA), P(MMA-BuA), and P(ST-BuA)], which were prepared in our laboratory by direct casting of polymer latexes synthesized by emulsion polymerization. These latex membranes exhibit preferential permeation towards water. Both water and ethanol permeations were non-ideal, with water permeation being enhanced by the presence of ethanol, and ethanol permeation being retarded by water. Pervaporation properties of a latex membrane can be affected significantly by membrane aging. The permeation rate decreases, while the separation factor increases, with increasing membrane aging time. The aging effect is due to the morphological changes of the latex membranes with time.