In the reported Asian lamivudine trial, the rate of hepatitis B e antigen (HBeAg) seroconversion, defined as HBeAg/hepatitis B virus (HBV) DNA seroclearance and development of anti-HBe, during 52 weeks of treatment was only 13% to 16%. To evaluate whether any factors influenced HBeAg seroconversion, data from 345 patients in that trial were reanalyzed to correlate HBeAg seroconversion with variables including treatment, age, gender, body build, histology, baseline HBV-DNA levels, and alanine transaminase (ALT) levels. Exploratory analysis using stepwise modeling revealed that HBeAg seroconversion correlated highly with pretherapy ALT (P <.001) followed by lamivudine therapy (P =.013), but only marginally with baseline HBV-DNA (P =.071) and cirrhosis (P =.066) for lamivudine 100 mg and placebo comparison. Among these four variables, only pretherapy ALT still had a highly significant (P <.001) correlation and lamivudine therapy had a borderline association (P =.066) for lamivudine 25 mg and placebo comparison. Categorical analysis revealed that HBeAg seroconversion occurred earlier and the cumulative rate was significantly higher in patients with pretherapy ALT values over 2 times the upper limit of normal (ULN) as compared with treated patients with lower ALT levels or untreated control patients with the same ALT levels (P <.001, respectively). The highest HBeAg seroconversion rate was observed in 100 mg lamivudine-treated patients with ALT levels greater than 5 times the ULN (64%) compared with patients with ALT 2 to 5 times the ULN (26%, P =.03); and ALT less than 2 times the ULN, (5%, P <.001). These results suggest that pretherapy ALT is the strongest determinant for HBeAg seroconversion during lamivudine therapy, and should be considered in selecting patients for treatment.