Do the gains in confidence and economic well being that can come from participation in a microfinance programme reduce clients' vulnerability to HIV infection? Until now practical experience and an evidence base relating to such activities have been limited. This article reviews the evidence supporting an enhanced role for microfinance in HIV prevention activities. It describes the Intervention with Microfinance for AIDS and Gender Equity (IMAGE) - a South African case study that has been specifically designed to explore these relationships. The paper discusses the operational integration of microfinance and HIV prevention - highlighting challenges, emerging lessons and limitations in the light of international best practice and several years of field experience.