Thai patients enrolled in STACCATO with HIV/hepatitis B virus (HBV) co-infection and tenofovir/emtricitabine-based antiretroviral therapy (ART) were randomly assigned to continuous treatment or CD4 cell count-guided interruptions. HBV replication was suppressed below detection in 15/16 patients. Structured treatment interruption increased transaminases and HBV viraemia in five of six patients; one flare was severe. Conversion to anti-hepatitis Be occurred with continuous treatment only. Tenofovir/emtricitabine-containing ART is highly effective in controlling chronic HIV/HBV co-infection but treatment should not be interrupted.