Background: De novo combination of lamivudine (Lam) and adefovir (Adv) was not rarely used in clinical practice. However, head-to-head comparisons of entecavir (Etv) monotherapy with this combination in hepatitis B virus (HBV)-related compensated cirrhosis patients are unavailable. This study aimed to compare the efficacy and safety of Etv monotherapy with combination therapy in patients with HBV-related compensated liver cirrhosis. Methods: Treatment-naive patients with HBV-related compensated liver cirrhosis were recruited to receive either Etv monotherapy or a de novo combination of Lam and Adv. Data were collected at baseline and every 6 months thereafter. Results: A total of 578 patients (485 in Etv group, 93 in combination group) were included. Baseline characteristics were comparable between the two groups. At the end of 1, 2, and 3 years, HBV DNA was undetectable in 82.7%, 96.2%, and 94.3% of patients in the Etv group and 88.9%, 81.7%, and 84.6% in the combination group, respectively (all P>0.05). The cumulative virological breakthrough rate at 1, 2, and 3 years was 2.7%, 6.7%, and 9.8% in the Etv group and 2.9%, 13.3%, and 32.2% in the combination group, respectively (P=0.003). After propensity-score adjustment for age, sex, and baseline HBeAg, ALT, and total bilirubin, virological breakthrough was higher in the de novo combination of Lam and Adv (HR 2.83, 95% CI 1.37-5.86; P<0.01). The cumulative rate of liver-related events, including decompensation and hepatocellular carcinoma, at 1, 2, and 3 years was 2.9%, 4.2%, and 6.1% in the Etv group and 2.2%, 2.2%, and 6.7% in combination group, respectively (P=0.83). Biochemical response and serological response were similar between the groups. Conclusion: Etv treatment had less virological breakthrough and potentially higher HBV-DNA suppression than de novo combination of Lam and Adv during 3 years in treatment-naive HBV-related compensated liver cirrhosis.