 Tenofovir TDF has been demonstrated to have potency antiviral against the hepatitis B virus HBV in various multiple-centre trials, with no cases of resistance encountered. However, its efficacy and resistance profile in the Asian population, which constitute the majority of chronic hepatitis B CHB patients, is unknown. Compared to other nucleoside analogues, TDF has been associated with relatively high rates of hepatitis B surface antigen HBsAg seroclearance. It would be interested to see if this could be reproduced. The investigators plan to report the serologic and virologic results of our 140 nucleoside analogue-experienced patients who were commenced on TDF. 