The use of methadone in the treatment of drug dependence has provoked a good deal of controversy. However, it is clear that there is considerable variation between methadone treatment programmes and relatively little detail is available about the organization and operation of these programmes. This World Health Organization survey examines the content and structure of methadone treatment programmes, and particularly methadone maintenance programmes, in six countries. The six countries were Australia, Canada, France, the Netherlands, Thailand and the UK. The report presents information about the extent of national problems and about such issues as type of dispensing practices, dose- and time-limits for prescribing methadone, programme entry criteria, staffing, integration with other services, and urine testing. Developments and trends during the decade 1980-1990 are discussed and implications for further research and programme development are presented.