Serum α-fetoprotein concentration were compared with the alteration of serum GPT activity in patients with acute hepatitis, patient with fluminant hepatitis, patients with subacute hepatitis, patients with chronic hepatitis (active form), patients with chronic hepatitis with sublobular hepatic necrosis, patients with A type of liver cirrhosis and patients with A'type of liver cirrhosis. Time course of serum α-fetoprotein concetration and serum GPT activity were clasified into the following 6 types.: Type 1. the peak of serum α-fetoprotein concentration comes after peak of serum GPT activity. Type 2. both peaks overlaps with each other in terms of temporal alteration. Type 3. a peak elevation in serum α-fetoprotein concentration with flat moderately increased level of serum GPT activity. Type 4. both levels activity flucutuation without peak at increased levels. Type 5. a peak elevation in serum GPT activity without serum α-fetoprotein peak. Type 6. progressive increase in serum α-fetoprotein concentration over 2000 ng/ml with or without similar serum GPT activity increase. Type 1 and 2 were frequently observed in case of acute hepatitis, subacute hepatitis and chronic hepatitis. Type 3 and 4 were rather specific to liver cirrhosis. Type 5 was frequently observed in acute hepatitis and chronic hepatitis with sublobular hepatic necrosis. Type 6 was observed in hepatocellular carcinoma.