This tool contains practical advice on implementing HIV and hepatitis C (HCV) programmes with people who inject drugs. The tool does not seek to ignore the complex policy and legislative environment around drugs and injecting drug use in most countries, nor the need for advocacy to confront the stigma, discrimination and human-rights violations faced by people who inject drugs. However, it aims primarily to address the question: what can we do now, with the resources we have, in the kinds of environments we face, to prevent the spread of HIV and hepatitis C among people who inject drugs?