ENGLISH :
Background : Methadone maintenance treatment (MMT) has been the 'gold standard' pharmacotherapy treatment for illicit opioid dependence for over 30 years. It has been widely evaluated, and is generally claimed to be 'effective'. Methods : The objective of this paper is to review the rationale of MMT as an intervention for a biomedical disorder with primary social objectives as well as the methodological quality and evidence of MMT outcome research. Data sources included opioid dependence treatment practice, review and outcome research literature (1965-2001) in the form of peer-reviewed articles, books, monographs and reports that are preeminently cited and reviewed international studies on MMT. Results/Data Synthesis : Rigorous and appropriate evaluation (i.e., RCTs, intent-to-treat, patient-centered) methods in MMT evaluations are rare. Evidence of MMT's effectiveness on primary treatment objectives is mixed and appears to be largely partial and short-term. Positive outcomes may be the result of selection effects of compliant patients and loss in proportion when more rigorous standards of analysis are applied. Conclusions : The quality of existing MMT research, and evidence for its general effectiveness are limited. Key concepts of self-medication and psychiatric comorbidity are largely ignored in MMT treatment and research frameworks, although they may serve to explain MMT's limited treatment success. Emerging new opioid pharmacotherapies require the fundamental review of the existing MMT paradigm as well as the application of rigorous and appropriate evaluation methods for future treatment. (Review' s abstract)