Asai et al.: Effect of Ethanol on Iontophoresis of ALAThe effect of ethanol was investigated on iontophoretic transdermal delivery of 5-aminolevulinic acid through Yucatan micropig full-thickness skin. When 20 % ethanol was added into an aqueous 5-aminolevulinic acid solution, the iontophoretic permeation of 5-aminolevulinic acid through Yucatan micropig full-thickness skin was enhanced. The addition of ethanol also enlarged the partition of 5-aminolevulinic acid into Yucatan micropig full-thickness skin, which gave rise to enhancement of 5-aminolevulinic acid permeation. This result suggested that the combination system of iontophoretic delivery and 20 % ethanol could be a promising approach for the promotion of 5-aminolevulinic acid skin permeation.