The aim of this study is to evaluate the effectiveness of lamivudine treatment in both precore mutant and wild type of chronic hepatitis B (CHB) patients. The study was done on sixty CHB patients of both sexes seeking treatment in the Outpatient Department and admitted patients of Mymensingh Medical College Hospital. The patients were divided into two groups. Group A included chronic hepatitis B patients with raised ALT (> 80 u/l ) with HBeAg positivity, and group B included precore mutant variety of CHB patients with raised ALT (> 80 u/l) with HBeAg negativity. In Group-A, after 1 year of completion of lamivudine therapy there was 86.67% normalization of ALT, 23.33% HBeAg loss, 16.67% anti-HBeAg development and 73.33% HBV DNA loss. In Group-B, there was 76.67% normalization of ALT and 73.33% HBV DNA loss after 1 year of completion of therapy. In the present study, it was observed that lamivudine is equally effective in both wild and precore mutant variety of CHB patients. This was reflected by normalization of ALT and loss of HBV DNA. This study also shows the reappearance of HBV DNA during the later half of Lamivudine therapy which is due to YMDD mutation.