AIM: To study the effect of a one-year lamivudine regimen in patients with chronic hepatitis B. METHODS: Medical records of HBeAg negative hepatitis B patients who attended a hepatitis clinic in Tehran between March 2002-March 2004 were evaluated. The patients received 100 mg lamivudine tablets once daily for at least 12 mo. Liver enzymes and complete blood count were checked at baseline and the end of treatment (12th mo) and 6 mo after discontinuation of treatment. RESULTS: Of all patients, 24 were excluded. Of 71 patients left, 58 (81.7%) were men. Mean age of the patients was 38±14 years. Mean level of ALT in serum was 1437±205 nkat/L at baseline with a significant reduction at the end of treatment to a mean level of 723±92 nkat/L (P = 0.002). In 38 patients (53.5%), the ALT level was normal after one-year treatment. Five patients (7.3%) relapsed (biochemically) within 6 mo after discontinuing lamivudine therapy (the patients with good end of treatment response). Mean level of AST in serum was 1060±105 nkat/L at baseline which decreased significantly to 652±75 nkat/L at the end of treatment (P = 0.002). CONCLUSION: Over half (53.5%) of chronic hepatitis B patients with HBeAg negative have normal liver enzyme level at 12-mo lamivudine therapy. AIM: To study the effect of a one-year lamivudine regimen in patients with chronic hepatitis B. METHODS: Medical records of HBeAg negative hepatitis B patients who attended a hepatitis clinic in Tehran between March 2002-March 2004 were evaluated. The patients received 100 mg lamivudine tablets once daily for at least 12 months. Liver enzymes and complete blood count were checked at baseline and the end of treatment (12th mo) and 6 months after discontinuation of treatment. RESULTS: Of all patients, 24 were excluded. Of 71 Mean age of the patients was 38 ± 14 years. Mean level of ALT in serum was 1437 ± 205 nkat / L at baseline with a significant reduction at the end of treatment to a mean level of the 723 ± 92 nkat / L (P = 0.002). In 38 patients (53.5%), the ALT level was normal after one-year treatment. Five patients (7.3%) relapsed (biochemically) within 6 months after discontinuing lamivudine therapy the patients with good end of treatment response). Mean level of AS T in serum was 1060 ± 105 nkat / L at baseline which showed significantly reduced to 652 ± 75 nkat / L at the end of treatment (P = 0.002). CONCLUSION: Over half (53.5%) of chronic hepatitis B patients with HBeAg negative have normal liver enzyme level at 12-mo lamivudine therapy.