This paper seeks to outline the range and type of heterosexual behaviour in a large non-clinic cohort of homosexually active males. A cohort of 930 homosexually active men were interviewed as part of a prospective study of the sero-prevalence of HIV. The paper indicates that over 60% of these men have had at least one sexual experience with a female and that about 90% of these males have engaged in vaginal intercourse with a female. 12% of the cohort had sexual contact with females in the last year, and 5% had sex with females, in the month preceding interview. Amongst these behaviourally bisexual males the number of female partners is significantly lower than the number of male partners. However, the proportion of female partners with whom penetration occurs is very much higher than for male partners.