This article reviews recent studies investigating sexual practice among gay and homosexually active men in Australia. The concept of ethics, understood as practical techniques adopted for the achievement of certain implicit and explicit goals, provides a framework for understanding the relation between gay men's engagement with medicine and their sexual practice over time. I argue that rather than producing straightforward complacency, the introduction of highly active antiretroviral therapy provided the conditions of emergence of a partial revaluation of risk among many gay men. "Negotiated safety" and "barebacking" might be understood as historically situated prevention ethics, scientifically plausible in some circumstances. Though emerging prevention ethics pose challenges for education, the strategy of enabling gay men, in conversation with health authorities, to be responsible for evaluating risk, has been remarkably effective. Enhancing the viability of prevention ethics begs attention to the quality and availability of public contexts within which embodied and lived experience can be brought into articulation with medical knowledge, raising the value of what is here described as "counterpublic health."