The aim of present syudy is to analyze fatty acid composition in plasma phospolipids in patients with hepatocellular carcinoma (HCC) and live cirrhosis (LC) and to elucidate the significance of polunsaturated fatty acid on hepatocarcinogenesis. Arachidonic acid/Linoleic acid (AA/LA) molar ratios in plasma phosphatidylinositol in LC (1.42±0.29,p<0.01) and in HCC (1.24±0.12,p<0.001) were significantly lower than that in control subjects (2.78±0.16). The AA/LA molar ratio in plasma phoshatidylethanolamine in HCC(1.07±0.13) was significantly lower than that in control subjecls (1.94±0.21,p<0.01). The plasma lysophospatidyclholine (LysoPC) concentration in HCC (71.6±8.4nmol/ml, p<0.001) and in LC(80.9±12.0 nmol/ml, p<0.001) were siginificantly lower than that in control subjects (146.7±5.7nmol/ml). Plasma arachidonoy-LysoPC was siginificantly in HCC(3.2±0.5mol%) compared with that in LC (1.5±0.3mol%,p<0.01) and in control subjecys (1.9±0.1mol%,p<0.01). Plasma arachidonoy-LysoPC may play an importhant role in the pathophysiology of HCC patients.