In the context of international debates about ways to reduce the harms related to the use of illicit drugs and their control, this article explores the specific issue of coerced treatment of people who use drugs. It uses established standards of human rights and medical ethics to judge whether it is ethical to apply either of two types of coerced treatment (compulsory treatment and quasi compulsory treatment, or QCT) to any of three groups of drug users (non problematic users, dependent drug users and drug dependent offenders). It argues that compulsory treatment is not ethical for any group, as it breaches the standard of informed consent. Quasicompulsory treatment (i.e. treatment that is offered as an alternative to a punishment that is itself ethically justified) may be ethical (under specified conditions) for drug dependent offenders who are facing a more restrictive penal sanction, but is not ethical for other people who use drugs. The article also briefly reviews evidence which suggests that QCT may be as effective as voluntary treatment.