For normalization of the low levels of plasma polyunsaturated fatty acids (PUFA), a PUFA-supplemented diet including fishes and safflower oil was served for two weeks to nine patients with decompensated cirrhosis, whose linoleic, α-linolenic, arachidonic, eicosapentaenoic and docosahexaenoic acid levels in the plasma total lipid fractions were significantly low. Linoleic and eicosapentaenoic acid concentrations in the plasma total lipid fractions and eicosapentaenoic acid in the plasma phospholipid fractions were significantly increased following the administration of the PUFA-supplemented diet to these patients. Increases in relative composition of dihomo-γ-linolenic and eicosapentaenoic acids were also recognized in the plasma total lipid fractions. However, α-linolenic, arachidonic, and docosahexaenoic acids were not altered either in the plasma total lipid or phospholipid fractions. Clinical data such as serum glutamate-pyruvate transaminase activity and bilirubin levels showed no change during PUFA-supplemented diet. Supplementation with arachidonic acid itself to the diet, as well as fishes and vegetable oil, seems to be necessary to maintain normal composition of plasma fatty acids in patients with decompensated cirrhosis.