The provision of free anti-retroviral treatment for AIDS in Zanzibar since March 2005 is the result of enormous struggles at a global scale and has provided immense relief for sufferers. At the same time, the new "medicines of hope", as they quickly became known, have produced new uncertainties about how best to respond to HIV/AIDS, both for the infected individual and for the society at large. ART programmes make possible a biologised, pharmaceutical life. Drawing on three case studies this paper shows how HIV-positive people struggle to make decisions in an environment characterised by deep uncertainties about the nature and causes of HIV/AIDS in particular, and about the continuity of Zanzibari society in general. It argues that health interventions cannot be orientated to "life itself"; they must be attuned to the contexts in which life takes place. Analysing people's actions and behaviours in the context of their lives-as-lived throws light onto apparently irrational decisions and emphasises the importance of an in-depth understanding of local moral worlds and social contexts. © 2012 Copyright Taylor and Francis Group, LLC.