The WHO recommends antiretroviral therapy (ART) for most HIV-infected tuberculosis patients. To assess the impact of ART on tuberculosis case-fatality rates in Cambodia, we compared treatment outcomes of patients newly diagnosed with tuberculosis in 2004 (before implementation of ART clinics) with outcomes of patients diagnosed in 2005 (after these clinics opened). In 2004, 37% of HIV-infected tuberculosis patients died during TB treatment compared with 5% of HIV-uninfected tuberculosis patients. In 2005, 18% of HIV-infected tuberculosis patients died compared with 5% of HIV-uninfected tuberculosis patients. The case-fatality rate for HIV-associated tuberculosis decreased from 2004 to 2005, coincident with the introduction of ART.