Substitution treatment for heroin addiction, i.e., maintenance prescribing of opioid agonist drugs to opioid dependent subjects, has increased in the last decade. The article reviews substitution treatment in Canada, the United Kingdom, Australia, Israel, and France. The critical issues around substitution treatment are similar. The first key issue concerns the balance between making treatment accessible and attractive and minimizing diversion to the black market. The second issue concerns the role of primary care in delivering methadone maintenance treatment (MMT). In general, there has been increasing involvement of primary health care, with training and support for practitioners. However, there is uncertainty and official ambivalence over whether treatment should be restricted to specialist clinics and practitioners, or available through primary care. In addition, there is the problem of stigma being associated with both addiction and with substitution treatment. Treatment is often at odds with community values. This places enormous strains on substitution treatment and makes the treatment system vulnerable to shifting community support and abrupt politically-driven changes in policy. References