Lipid pattern and fatty acid composition of oral palatal epithelium were investigated in three groups of Sprague-Dawley rats: essential fatty acid (EFA)-deficient rats, which were fed diets containing 0.07 calorie% EFA for more than two generations; liver cirrhotic rats repeatedly injected with carbon tetrachloride; control rats fed standard pellets. The fatty acid pattern was studied in choline phosphoglycerides, ethanolamine phosphoglycerides, total phosphoglycerides, triglycerides and free fatty acids. Disturbances in the farry acid composition were seen chiefly in the EFA-deficient group, where marked reductions of the polyunsaturated fatty acids 18:2 and 20:4 (n-6) of the linolecic acid series were observed. At the same time, a compensatory increase was registered in the amount of 18:1 and 20:3 (n-9) of the oleic acid series. Corresponding findings were also found for the liver cirrhotic rats, except for the reduction of 18:2, but the changes of the fatty acid pattern in this group were not as marked as was observed for the EFA-deficient rats. In the lipid pattern no differences were seen between the three experimental groups, except for a somewhat higher content of lipid phosphorus and cholesterol in the EFA-deficient rats and a higher amount of free fatty acids in the liver cirrhotic group compared with the control rats. Changed physiological condition of the oral mucosa was suggested to be a result of the observed disturbances in the fatty acid composition of the oral epithelium.