In order to evaluate the clinical significance of serum sialic acid (SA) in Primitive hepatic carcinoma (PHC) , It was determined in 46 cases of PHC, 210 cases of benign non-cancer hepatic disease (BHD) , and 100 cases of healthy blood donor (HBD) .They were significantly higher in PHC than in HBD and BHD (P<0.001) , and correlated with patient's stage or size of tumor and curative effect in PHC.It shows that the determination of serum SA has significantly clinical value in PHC.