Abstract: Objective To study the effects of antiviral therapy using lamivudin on patients with primary liver cancer complicated by hepatitis B virus. Methods Between 2002 and 2006, 58 patients with primary liver cancer complicated by hepatitis B virus were randomly divided into two groups: the control group (n=27) received hepatectomy only, and the treatment group (n=31) received hepatectomy and antiviral therapy using lamivudine. The liver function, suppression of HBV-DNA, HBeAg seroconvert rate, tumor recurrent rate and survival rate for the two groups were observed and calculated. Results The ALT level in the treatment group was lower than that in the control group 6 months after surgery. Child-pugh scores of two-year and three-year in the treatment group were significantly lower than those in the control group (7.4±1.7 vs. 8.9±1.8，7. 8±1.5 vs. 10.2±2.2, respectively, P< 0.05). In the treatment and control groups, the one-year HBV-DNA suppression rate was 100% vs. 3.7% (P< 0.05). Although there was not significant difference in one-year and two-year tumor recurrent rate between the treatment and control groups, three-year tumor recurrent rate in the treatment group was lower than that in the control group (45.2% vs. 59.3%，P< 0.05). In treatment group and control group, the three-year survival rates were 77.4％ and 54.8% respectively (P< 0.05). Conclusion Antivirus therapy using lamivudine may suppress the HBV reaction, decrease the tumor recurrent rate and prolong the survival for patients with primary liver cancer complicated by hepatitis B virus.