AIM: To evaluate the efficacy and safety of telbivudine (LDT) in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients who have high baseline alanine aminotransferase (ALT) levels between 10 and 20 times the upper limit of normal. METHODS: Forty HBeAg-positive CHB patients with high baseline ALT levels between 10 and 20 times the upper limit of normal were enrolled and received LDT monotherapy for 52 wk. Another forty patients with baseline ALT levels between 2 and 10 times the upper limit of normal were included as controls. We compared the virological, biochemical, serological and side effect profiles between the two groups at 52 wk. RESULTS: By week 52, the mean decrease in hepatitis B virus (HBV) DNA level compared with baseline was 7.03 log(10) copies/mL in the high baseline ALT group and 6.17 log(10) copies/mL in the control group, respectively (P < 0.05). The proportion of patients in whom serum HBV DNA levels were undetectable by polymerase chain reaction assay was 72.5% in the high baseline ALT group and 60% in the control group, respectively (P < 0.05). In addition, 45.0% of patients in the high baseline ALT group and 27.5% of controls became HBeAg-negative, and 37.5% of those in the high baseline group and 22.5% of controls, respectively, had HBeAg seroconversion (P < 0.05) at week 52. Moreover, in the high baseline group, 4 out of 40 patients (10%) became hepatitis B surface antigen (HBsAg)-negative and 3 (7.5%) of them seroconverted (became HBsAg-positive). Only 1 patient in the control group became HBsAg-negative, but had no seroconversion. The ALT normalization rate, viral breakthrough, genotypic resistance to LDT, and elevations in creatine kinase levels were similar in the two groups over the 52 wk. CONCLUSION: High baseline ALT level is a strong predictor for optimal results during LDT treatment.