Issues: We present key aspects of our paper, commissioned by UNAIDS in 2005, entitled, “Revisiting the ethics of HIV prevention research in developing countries.” In 2004 and 2005 we witnessed the closure or suspension of three international clinical trials testing tenofovir in the prevention of HIV infection in high risk groups due to the failure to provide free treatment to those who seroconvert during the conduct of the study. We examine critically moral claims for the provision of treatment to those who seroconvert in HIV prevention trials and ask whether it is a matter of moral obligation or moral negotiation? Description: Using the tools of philosophical and regulatory analysis we examine the moral foundations of research ethics, international regulation, and the contemporary literature in search of valid arguments in support of a moral obligation to treat. Arguments supporting the obligation to provide such treatment are found in a wide variety of documents. These claims are variously rooted in the demand to compensate for research-related injury, maximization of research benefit, justice as reciprocity, and justice as equality. Lessons learned: Our analysis reveals that there is as of yet no robust moral argument supporting a moral obligation to provide treatment to participants in HIV prevention trials who seroconvert. We argue that moral negotiation offers distinct advantages over moral obligation. Moral negotiation finds support in the principle of respect for communities that holds researchers responsible to respect communal values, protect and empower social institutions and abide by the decisions of accepted communal authorities. Recommendations: Moral negotiation, rather than moral obligation, reduces the chance of polarization of positions by inviting trial participants, sponsors, researchers and all other involved parties to the table for discussion. Moral negotiation favors middle ground solutions that fit the specific health needs and priorities of the community in question.