This paper considers the role of conditional cash transfers as a mechanism of governing health risk by buying behaviour change in sexual practice. Conditional cash transfers have come to be identified as a potential solution to the problem of HIV prevention, and as such look likely to be applied throughout countries with high prevalence rates in sub-Saharan Africa. The paper considers the implications of two pilot studies in Tanzania and Malawi for governing the risk of HIV infection. It outlines the problem of behaviour change and individual rationality, the potential of conditional cash transfers as a relatively inexpensive programme with high outcomes, and some of limitations and implications of these initiatives for individual bodies, rationality and global health governance. The paper makes the argument that conditional cash transfers should be met with caution and that governing health risk by buying behaviour represents the intersection of biopolitical control with neoliberal forms of economic incentive through financial gain. The balancing of long term health needs with short term financial gain induces will to change behaviour: the problem being the sustainability of such change in the absence of financial gain and the long term consequences of constructing behaviour.