Recent epidemiological studies have shown fairly convincingly that in high-risk populations in sub-Saharan Africa, male circumcision is associated with a reduced risk of HIV infection. Following a consultation at the XIII International AIDS Conference in July 2000 in Durban, there was growing interest in such an intervention. This paper explores what is known about male circumcision, the risks associated with it, its relationship with sexual health, including HIV and other sexually transmitted infections (STIs), and the potential problems with implementing circumcision as an intervention internationally, particularly in traditionally non-circumcising communities and those where access to medical facilities is limited. Proponents of male circumcision as an HIV prevention strategy are convinced and convincing, but circumcision is a surgical procedure with associated risks and has strong religious and cultural significance for many groups. Hence, there are ethical and practical barriers to implementing it as a public health intervention. The evidence suggests that circumcision may reduce the risk of infection, but circumcision does not appear to have any impact on transmission rates from HIV positive men to their partners. Until we know why and how circumcision is protective, exactly what the relationship is between circumcision status and other STIs, and whether the effect seen in high-risk populations is generalisable to other groups, the wisest course is to recommend risk reduction strategies of proven efficacy, such as condom use.