To investigate the roles of apoptosis and the Fas system (Fas, Fas ligand, soluble Fas) in the process of liver cirrhosis (LC) converting into hepatocellular carcinoma (HCC), expression of Fas and Fas ligand (FasL) in 49 LC and 36 HCC samples was detected by immunohistochemical method. Apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method. Serum soluble Fas (sFas) levels in 28 cases of LC and 27 cases of HCC were measured by enzyme-linked immunosorbent assay (ELISA) method. Compared with LC, apoptotic indices (AI) in HCC tissues were significantly reduced (P<0.001), expression of Fas was decreased (P<0.05), and that of FasL was increased (P<0.05). Serum sFas levels in HCC patients were significantly higher than those in normal controls. Down-regulation of Fas expression, up-regulation of FasL expression in hepatocytes and elevation of sFas level in serum might contribute to tumor escape from immune surveillance of the body. Apoptosis and the Fas system are significantly involved in the process of liver cirrhosis converting into hepatocellular carcinoma.