AIM: To further evaluate the relationship between BSA and the effects of lamivudine in a greater number of cases and over a longer period of observation than in our previous evaluation. METHODS: We evaluated 249 patients with chronic hepatitis B. The effects of treatment for one year (n = 249), two years (n = 147), and three years (n = 72) were evaluated from the levels of serum ALT and HBV-DNA, as biological and virological effects (undetectable levels by PCR), respectively. Moreover, several variables that could influence the response to treatment, including ALT, albumin, bilirubin, platelet counts, BSA, HBV-DNA, and HBeAg were analyzed. RESULTS: For 1-year treatment, multivariate analysis revealed that BSA (P = 0.0002) was the only factor for the biological effect, and that ALT (P = 0.0017), HBV-DNA {P = 0.0004), and HBeAg (P = 0.0021) were independent factors for the virological effect. For 2-year treatment, multivariate analysis again showed that BSA (P = 0.0147) was the only factor for the biological effect, and that ALT (P = 0.0192) and HBeAg (P = 0.0428) were independent factors for the virological effect. For 3-year treatment, multivariate analysis, however, could not reveal BSA (P = 0.0730) as a factor for the normalization of ALT levels. CONCLUSION: BSA is a significant predictor for the normalizing the effect of lamivudine therapy on ALT for an initial 2-year period, suggesting that lamivudine dosage should be based on the individual BSA. To further evaluate the relationship between BSA and the effects of lamivudine in a greater number of cases and over a longer period of observation than in our previous evaluation. METHODS: We evaluated 249 patients with chronic hepatitis B. The effects of treatment for one year (n = 249), two years (n = 147), and three years (n = 72) were evaluated from the levels of serum ALT and HBV- DNA, as biological and virological effects (undetectable levels by PCR), respectively. RESULTS: For 1-year treatment, multivariate analysis revealed that BSA (P = 0.0002 ) was the only factor for the biological effect, and that ALT (P = 0.0017), HBV-DNA {P = 0.0004), and HBeAg analysis again showed that BSA (P = 0.0147) was the only fact For 3-year treatment, multivariate analysis, however, could not reveal BSA (P = 0.0730) as (P = 0.0192) and HBeAg a factor for the normalization of ALT levels. CONCLUSION: BSA is a significant predictor for the normalizing the effect of lamivudine therapy on ALT for an initial 2-year period, suggesting that lamivudine dosage should be based on the individual BSA.