Gender shapes the experience of drug use and its associated risks. In most parts of the world, however, harm reduction and drug treatment programmes that tailor their services to meet women's needs are rare or nonexistent. Many existing services inadvertently exclude women, and discriminatory policies and social stigma drive women drug users from care and expose them to human rights abuses. Women drug users often provide sex in exchange for housing, sustenance and protection, suffer violence from sexual partners and practise unsafe sex. This paper, drawing upon evidence from existing studies, examines ways in which gender-related factors can increase women drug users' vulnerability and decrease their access to harm reduction, drug treatment and sexual and reproductive health services. It recommends designing services with low-threshold access for women drug users that help them to become more independent, involving the women in designing services and policies, making programmes available for mothers, incorporating sexual and reproductive health into harm reduction services, providing gender-sensitive drug treatment and integrated harm reduction programmes for drug-using sex workers, connecting with domestic violence and rape prevention services and educating mainstream providers. Overall, investigating the circumstances women drug users face will help to formulate policies and programmes that better serve women who use drugs.