Seventy-five homosexual men with recently acquired HIV were interviewed about their risk behaviour. Fifty-nine reported unprotected anal intercourse, and one shared injecting equipment, with a partner not known to be HIV negative. Of the remaining 15, 11 reported protected anal intercourse. In five of the 15 we judged oral sex to be the most likely source of infection, including three men who had a genital piercing. The possible transmission risk from genital piercing should be investigated.