Epidemiological data in 13 cases of sexual assault on men who attended a sexual assault referral centre are presented. All the assailants were male. The sexual orientation of the victims was predominantly heterosexual (7 of 13), 3 considered themselves to be homosexual and 3 were confused about their sexual orientation. The average age at the time of assault was 21.6 years. The most common form of assault was anal intercourse which occurred in 8 cases, followed by forced oral penetration which occurred in 6 cases. The proportion of known:unknown assailants (8:5) shows similar characteristics to those seen in female rape, use of weapons and multiple assailants were more common in assault on men. Seven men (54%) developed psychological problems following assault, and this was their main reason for presentation to the centre.