Ethanol fermentation is inhibited by the products of the reaction and the productivity is reduced with increase in the concentrations of products. By removing the products from the fermentor, a high productivity can be maintained during fermentation. In this paper, we propose a new method of long-term fermentation with minimal wastewater, and evaluate the effect of removal of ethanol by pervaporation (PV) on ethanol fermentation. Three types of fermentation experiments were carried out; batch fermentation as the standard process, fed-batch fermentation without PV, and fed-batch fermentation with PV. Glucose and immobilized baker＇s yeast were used for the fermentations. A module of a hydrophobic porous membrane made of polypropylene (PP) was used for the PV process. Fed-batch fermentation with or without PV was carried oat for 72 h, and the feed rate (F) was equal to the sum of the production rate (P) and drain rate of broth (W), and was=1 l/12 h. When the removal ratio (R) was adjusted to 84.4%, the concentration of ethanol in the broth remained almost constant at 50 g/l, and the apparent rate of ethanol production was 2 times higher than that in fermentation without PV. Total ethanol produced was 780 g, and the conversion efficiency of glucose to ethanol was 96.3% of the theoretical yield. The amount of wastewater was 38.5% of that discharged from the conventional batch process. Furthermore, it was shown that as the riverse of inhibition constant (1/K-i) approached zero at R=100%, tbe effect of byproducts on tbe fermentation was negligible, thus indicating that in the presence of PV, the reduced ethanol productivity was only due to ethanol inhibition under present conditions.