 Tuberculosis TB remains one of the important infectious diseases worldwide. Timely implementation of optimized anti-tuberculous therapy is still the mainstay to prevent further transmission of TB. However, hepatitis during anti-tuberculous treatment HATT has been an obstacle in managing TB patients, especially in those with viral hepatitis. A previous study revealed the risk of HATT is significantly higher in TB patients with high serum hepatitis B virus HBV DNA level than those with low HBV DNA level 39 vs. 11, the latter cases have a similar risk of HATT as those without viral hepatitis 14. Based on these findings, we thus hypothesize that the risk of HATT in TB patients with high baseline serum HBV DNA level can be reduced by concomitant use of anti-HBV agent. In this proposal, we will conduct a prospective randomized clinical study to assess the reduction of HATT risk by using entecavir in TB patients with high baseline serum HBV DNA level, and to evaluate the risk of other treatment-related adverse events in two hospitals. From January 2012 to June 2014, subjects with culture-confirmed TB and aged from 18 to 80 with high serum HBV viral load prior to anti-tuberculous treatment will be enrolled and randomized into either study or control group. High serum HBV viral load is defined as 20,000 and 2,000 IUmL for HBeAg-positive and HBeAg-negative subjects, respectively. In addition to standard anti-tuberculous treatment, subjects in the study group will receive entecavir BARACLUDE 0.5 mg per day during anti-tuberculous treatment and for 6 months after stopping anti-tuberculous treatment. Hemogram, liver function, renal function, and serum HBV viral load will be regularly monitored to detect the development of HATT and other adverse events. In this study, HATT is defined as fulfilling anyone of the following conditions: 1 increase in serum AST andor ALT level of 3 times upper limit of normal ULN with symptoms if baseline liver function is normal; 2 increase in serum AST andor ALT level of 5 times ULN without symptoms if baseline liver function is normal; 3 increase in serum AST andor ALT level of 2 times baseline if baseline liver function is abnormal; and 4 increase in serum total bilirubin level of 2.5 mgdL. 