Ethanol has been widely used as a percutaneous penetration enhancer and its action on the cutaneous barrier has been well studied. Ethanol may have a "tluidisation" effect on the intercellular lipids of the stratum comeum, the insertion of ethanol between endogenous lipid provokes an increase in structural disorder. This effect has been reported to occur at low ethanol concentrations (25% v/v) (1) and has been compared to the effect of increasing skin temperature (2). An increasing extraction of epidermal lipids with increasing ethanol concentrations, has also been reported as the major mechanism by which alkanols promote transdermal penetration (3). It has been observed that very high alkanol concentrations (> 75% ), result in significant lipid extraction and with 100% ethanol treatment, full thickness skin appears to be devoid of its barrier and even behaves like stripped skin ( 1,4 ). Bath contact time and ethanol concentration influence whether or not the effects of ethanol treatment are reversible (1,3-5). As in the skin, the action of ethanol on oral mucosa depends upon the amount of alcohol in contact with the membrane and the contact time (6). As the ethanol concentration is increased, there is a greater lipid extraction, accompanied by a reorganization of the intercellular lipids. Therefore, one can expect that treatment with high ethanol levels for long periods, will produce a greater perturbation of the membrane. Based on the evidence described above, in this study we have addressed the following objectives: (a) To determine the action of ethanol as a lipid extracting solvent, on keratinized oral mucosa. (b) To separate, identify and quantify the Iipids present in the hydroalcoholic treating solutions. (c) To determine the relative importance of ethanol concentration and contact time on lipid extraction.