The study was to evaluate clinical the efficacy and safety of entecavir in Vietnam chronic hepatitis B patients. The results indicated 30.2 percent, 73.8 percent and 87.3 percent of patients achieving undetectable HBV DNA in both treatment groups after 12, 24 and 48 weeks, respectively. HBeAg seroconversion occured in 16.3 percent, 20.4 percent va 49.9 percent after 12, 24 and 48 weeks, respectively. Normalization of alanine aminotransferase levels was 57.9 percent, 65.9 percent and 77 percent after 12, 24 and 48 weeks, respectively. Histologic improvement after 48 weeks of entecavir treatment occurred 80 percent in HBeAg(+) group and 60.7 percent in HBeAg(-) group. Highly percent of patients in both treatment goups disappeared clinical symptoms fatigue and anorexia. The most common side effects were headache, nasopharyngitis In conclusion, Entecavir offers to control HBV replication in both group HBeAg positive and HBeAg negative, normalization of alanine aminotransferase levels and HBeAg seroconversion achieve relatively high, good clinical improvement, safety profile, this suggests that entecavir should be considered as a primary therapy for HBeAg positive and HBeAg negative chronic hepatitis B.