 Studies indicate that 70 to 80 of HIV infected patients have or have had HBV infection and that 10 are HBV carriers. Lamivudine therapy for treatment of HBV in HIV infected patients has limited long-term efficacy due to the development of resistance mutations. Telbivudine is a thymidine analogue with excellent HBV inhibitory activity but no anti-HIV activity. The primary objective of this study is to evaluate the safety and anti-HBV activity of telbivudine alone and in combination with a lamivudine-based highly active antiretroviral therapy HAART regimen in patients coinfected with HBV and HIV. 