BACKGROUND The aim of this study was to evaluate the dietary supplementation with omega-3 and omega-6 long-chain polyunsaturated fatty acids on the fatty acid composition of plasma and red blood cell membranes in rats with thioacetamide-induced liver cirrhosis. METHODS Thirty-eight female Wistar rats were given 300 mg thioacetamide/L in drinking water for 4 months to induce the experimental liver cirrhosis. Sixteen rats were used as controls. After treatment with thioacetamide, nine rats of each group were killed. Then, thioacetamide-treated rats were divided into three new groups, each receiving a different diet for 2 weeks: a semipurified diet (n = 9), the same diet supplemented with omega-3 long-chain polyunsaturated fatty acids (n = 10), or the same semipurified diet supplemented with omega-3 and omega-6 long-chain polyunsaturated fatty acids simultaneously (n = 10). The remaining control rats were fed the semipurified diet. Liver histology and plasma and erythrocyte fatty acid composition were assessed. RESULTS An apparent improvement of the histological damage took place in the rats fed the omega-3+ omega-6-supplemented diet. The diet supplemented with polyunsaturated fatty acids of the omega-3 series induced increases in the omega-3 long-chain polyunsaturated fatty acid levels in total plasma lipids, plasma lipid fractions and in erythrocyte phospholipids, and decreases in omega-6 long-chain polyunsaturated fatty acids in erythrocyte phospholipids during the recovery of rats with thioacetamide-induced liver cirrhosis. The administration of the diet supplemented with both omega-3 and omega-6 long-chain polyunsaturated fatty acids contributed to increase the levels of total plasma saturated, monounsaturated, and omega-6 long-chain polyunsaturated fatty acids from cirrhotic rats. CONCLUSIONS We conclude that the simultaneous supply of long-chain fatty acids of the omega-3 and the omega-6 series can be beneficial to improve the fatty acid status of this experimental model of liver cirrhosis.