The incidence of HIV infection among women in Europe and the US is growing rapidly. Women who inject drugs are particularly vulnerable--they may acquire the infection through sharing injecting equipment and through sexual contact with an infected male. Opioids and stimulants are reputed to have different effects upon sexual activity and a sex life enhanced by drugs may increase the risk further. In the context of two larger studies of HIV-related risk behaviours among opioid and amphetamine users in the North West of England, the sexual behaviour and sharing of two groups of female injectors were compared, one whose primary use was heroin, the other amphetamine. Reported incidence of sharing was similar and high. Marked differences were observed in sexual behaviour, amphetamine injectors reporting greater interest in sex and greater frequency of intercourse. However, more of them perceived their personal risk to infection through unprotected sex as negligible. Over 80% in both groups had engaged in unprotected sex in the 6 months prior to interview. Women injectors tend to have injecting partners--more research is needed if health education strategies are to be devised that will protect them.