Adolescents with haemophilia comprise 44% of the reported AIDS cases in teenagers. Unprotected sexual intercourse among this group increases the risk of HIV transmission. Understanding the influences which others may have on the sexual behaviour of adolescents with HIV and haemophilia may lead to the development of effective risk reduction strategies. An evaluative instrument, administered to 307 HIV-infected adolescents with haemophilia, assessed their behavioural stage of change (Prochaska & DiClemente), attitudes, beliefs and behaviours about safer sex practices. The influence of parents, peers and sexual partners on sexual behaviour was compared between (1) those who were sexually experienced and (2) and those who were sexually inexperienced. Barriers and facilitators to practising safer sex were identified. Although parents influenced the sexual behaviour of both groups, this influence was significantly greater in the sexually inactive group. Fewer than 20% reported that their peers impacted their decisions about sexual behaviour. Eighty-six per cent of the sexually active indicated that partners significantly impacted their sexual decisions, while 60% of the sexually inactive indicated that future partners would affect their decisions about sex. Most participants agreed that disclosure of HIV status before intercourse was desirable, but only 31% of the sexually active said they told every partner. Fear of rejection or a negative reaction from the partner, and lack of communication skills were the greatest barriers to disclosure of HIV status and practising safer sex. This study indicates that behavioural interventions for both groups should focus on developing communication skills and self-efficacy. Interventions should include the key influences for each group--parents for the sexually inactive and partners for the sexually active.