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Asymmetrically crosslinked PVA membranes which have distribution of crosslinking density along the membrane cross section were prepared and their pervaporation performances were studied. Both the water flux and the water selectivity were larger when the feed liquid was in contact with the less crosslinked side (DOWN), compared with the case of the membrane being upside down (UP). The differences in the performance between DOWN and UP were larger when the asymmetricity was larger. These results suggested that the selectivity is determined mainly by the behavior of the permeate side.