In this paper, I discuss the parallels between responses to syphilis in nineteenth century Britain and HIV/AIDS in contemporary Africa. In each case, an incurable disease connected with sexual behaviour aroused fear, stigmatisation and moralistic responses, as well as a desperate scramble to find an effective means of control. In both cases, circumcision of adult males, and then of children or infants, was proposed as the key tactic. In the ensuing debates over the effectiveness and propriety of this approach, three questions occupied health authorities in both Victorian Britain and the contemporary world: (1) Were circumcised men at significantly lower risk of these diseases? (2) If there was evidence pointing to an affirmative answer, was it altered anatomy or different behaviour that explained the difference? (3) Given that circumcision was a surgical procedure with attendant risks of infection, was it possible that circumcision spread syphilis or HIV? I show that in both situations the answers to these questions were inconclusive, argue that circumcision played little or no role in the eventual control of syphilis and suggest that attention to nineteenth century debates may assist contemporary policy-makers to avoid the treatment dead-ends and ethical transgressions that marked the war on syphilis.