Abstract: This report, which provides a knowledge base for the development of methadone maintenance treatment clinical guidelines in Switzerland, reviews the world-wide literature (except for Switzerland, which is the subject of a separate investigation) on such treatment and existing guidelines. Articles on methadone maintenance treatment and concurring treatment modalities are discussed in detail, as well as existing knowledge about specific populations, such as pregnant addicts and addicts with HIV or tuberculosis. Research on prognostic factors to patients’ responses to treatment and perceptions of opiate dependent persons are also reviewed to ascertain their value to practitioners in managing methadone maintenance treatment and in assessing the best possible treatment. A final chapter describes other substitution treatments in comparison to methadone maintenance and synthesizes the information of the review into a structured information source for thinking about guideline development.