Objective To investigate the expression of MUC1 in primary liver carcinoma (PLC) and in cirrhotic liver tissue and its clinical significance in the diagnosis and immuotherapy of PLC. Methods The expression of MUC1 was examined by immunohistochemical analysis in 43 samples of primary liver carcinoma (PLC) , incluing 34 samples of hepatocellular carcinoma (HCC), 9 samples of cholangiocarcinoma (CC) ;and 12 samples of cirrhotic liver tissue and 6 samples of normal liver tissues. Results Immunohistochemical analysis showed over- expression of MUC1 in PLC , which aberrantly localized in the cancer cell membrane; while expression of MUC1 was detected only in 2 cirrhotic liver samples,and no expression in normal liver tissue. The expressional level of MUC1 in PLC was significantly higher than that in cirrhotic and normal liver tissue ( P 0.05),but the expressional levels between with portal cancer emboli group and without portal cancer embloli group was significant difference( P