To evaluate the long-term efficacy of entecavir in nucleoside-naïve chronic hepatitis B patients.One hundred and sixty-seven patients treated with entecavir 0.01mg, 0.1mg or 0.5mg for 24-52weeks in Phase II studies entered rollover study ETV-060 and received entecavir 0.5mg daily. Responses were evaluated among patients with available samples.After 96weeks in ETV-060 (120-148weeks total entecavir treatment time), 88% (127/144) of patients had HBV-DNA <400 copies/ml; 90.1% (128/142) had alanine aminotransferase (ALT) 1x the upper limit of normal (ULN) among those with abnormal baseline ALT; and 26% (32/121) achieved HBe seroconversion among those HBeAg(+) at baseline. A subset of 66 patients received entecavir 0.5mg (approved dose) from Phase II baseline: at week 96 in ETV-060, 83% (48/58) had HBV-DNA <400 copies/ml, 88% (52/59) had ALT 1x ULN, and 20% (10/49) achieved HBe seroconversion. Twenty-one out of 66 patients had paired baseline and on-treatment biopsies: 100% (21/21) and 57% (12/21) demonstrated histologic improvement, and improvement in fibrosis, respectively, over 3years. The 3-year cumulative probability of resistance was 3.3% for all patients and 1.7% for the 0.5mg subset.Long-term entecavir for nucleoside-naïve patients resulted in high rates of virological, biochemical, and histological response, with minimal resistance.