Alpha-fetoprotein (AFP) was, first described in the human fetus in 1956 and became a marker protein of primary liver cancer in adults. Serum AFP level were measured by radioimmunoassay in 212 patients with a variety of malignant and nonmalignant diseases to determine the incidence of levels elevated above 40ng/ml. The results obtained are as follows: In 44 cases of total 212 patients, abnormal AFP levels above 40ng/ml in serum were measured; 24 of 31 patients with primary hepatocellular carcinoma & primary hepatocellular carcinoma with liver cirrhosis (77.4%), 7 of 51 patients with only liver cirrhosis (13.7%), 4 of 10 patients with metastatic liver cancer (40.0%), 4 of 15 patients with chronic hepatitis (26.7%), 2 of 23 patients with acute hepatitis (8.7%), and each one patient with 6 pancreatic carcinoma and 9 cholangiocarcinoma had elevated serum AFP levels. One pregnant woman with gestation 35 weeks had elevated level, but within norman limit during pregnancy.