Lamivudine treatment in hepatitis B e antigen (HBeAg)-negative and hepatitis B virus (HBV) DNA-positive chronic hepatitis B (CHB) patients is associated with poor sustained response. A previous study has shown that short-term lamivudine therapy in HBeAg-positive patients with alanine aminotransferase (ALT) > 5x upper limit of normal (ULN) could achieve a high HBeAg response rate and low lamivudine resistance rate. We, therefore, prospectively treated 85 HBeAg-negative CHB patients with ALT > 5x ULN by lamivudine for 6-12 months. The mean pretreatment levels were as follows: ALT (normal < 36 U/I) 533 U/I (range: 180-2,418 U/I); total bilirubin (normal < 1.3 mg/dl) 2.0 mg/dl (range: 0.2-29.6 mg/dl), HBV DNA (normal, undetectable) 1.6 x 10(8) copies/ml (range: 1.4 x 10(5)-1.7 x 10(9) copies/ml). After a mean of 7.4 months (6-12 months) treatment, 69 (81%) patients achieved complete response. In a follow-up, 12 months after stopping lamivudine therapy, 33 (39%) patients showed sustained complete response. Patients with sustained response were younger than the relapsed patients (39.7 +/- 11.9 years versus 47.0 +/- 10.3 years; P = 0.005). The emergence of lamivudine-resistant variant HBV was documented in two patients (2%). It is concluded that in HBeAg-negative chronic hepatitis B patients with ALT levels above 5x ULN, a 6-12 month course of lamivudine therapy may achieve sustained an off-treatment response in approximately one-third of patients.