Abstract: A new method for assaying the activity of DCP in 41 patients with hepatocellular carcinoma （HCC）, other malignancies and healthy subjects, using staphylocoagulase, was reported. levels of DCP in healthy subjects were under 60mU/ml. Of 41 HOC patients, 70.7% had elevated DCP values, It showed a significant high value （P＜0.01） as compared with that in other malignanancies and healthy subjects.The diagnostic positive rate in 17 cases of small HCC was 76.4%. Combined measurement of DCP and α-FP gave a complementary information, the positive rate increased to 80.4%. DCP levels reduced to the normal limit were found in 4 patients two weeks after hepatectomies. This result indicates that DCP is probably synthesized by hepatoma cells. In conclusion, DCP may be a sensitive, specific and useful tumor marker in the diagnosis of HCC, especially in small HCC.