To compare the efficacy of Lamivudine (LAM) monotherapy and combination therapy with Adefovir Dipivoxil (ADV) for patients with hepatitis B virus (HBV) -related decompensated cirrhosis for 2 years. A total of 115 patients with HBV-related decompensated cirrhosis were erolled in this study, among 60 patients were treated with LAM combined with ADV and 55 were treated with LAM. The liver and kidney functions, HBV DNA, HBV-M, AFP, Ultrasond or CT scan of liver were tested every 1-3months. the treatment efficacy was evaluated by month 12 and 24. By month 12, the HBV DNA negative rates of combination therapy group and LAM monotherapy group were 51.1% (45 cases) and 47.5% (40 cases) respectively, by month 24 the rates were 86.7% and 60.0% respectively. By month 24 the HBeAg negative rates of combination therapy group and LAM monotherapy group were 43.5% and 30.0% respectively, with significant difference existed between the two therapy groups (P values is less than 0.05). By month 24, the ALT normalization rates of the two groups were 88.9% and 72.5% respectively. Viral breakthrough happened in 2 cases (4.4%) by month 12 and 3 cases (6.7%) by month 24 in LAM and ADV combination group, but no viral resistance observed. Viral breakthrough happened in 9 cases (22.5%) by month 12 and 15 cases (37.5%) by month 24 in LAM monotherapy group with viral resistance observed in 7 cases (17.5%) by month 12 and 13 cases (32.5) by month 24. Significant difference existed between the two groups (P is less than 0.05). Improvement of liver function was more obviously in the combination group. The accumulative total mortality or liver transplantation rate were 16.7% and 20.0% respectively in combination therapy group and LAM monotheapy group. No renal dysfunction observed in both groups. LAM combined with ADV is better choice for patients with HBV-related decompensated cirrhosis as compared to LAM monotherapy.