OBJECTIVES: In the past, five different monitoring systems were used in the various areas of the care supply for substance-related problems in Switzerland, without any real coordination between them. In 1999, a project aiming at the harmonisation of these five monitoring systems was launched by federal agencies. A further aim was to ensure compatibility with the Treatment Demand Indicator (TDI) adopted as European standard. METHODS: The different steps of the conceptualisation process and their rationales are described. They involve a first phase of consultation among all key players, a second phase of preliminary realisation according to the target criteria, a third phase of probation by the application of a pilot survey, and a last phase of consolidation and adjustments before the official implementation. RESULTS: A comprehensive and flexible monitoring system was settled for all fields of the addiction care in Switzerland. It consists of a fully standardised pool of core items to be shared by the five treatment sectors as well as optional items intended for specific needs. The practical aspects of the implementation, like data protection, organisation of data collection, and valorisation of the results are presented. The first experiences in the different treatment sectors are also reported. CONCLUSION: The implementation of "act-info" is still an ongoing process that began in 2003. Since 2005, the new monitoring system is well implemented in three out of five treatment sectors, whereas its introduction proves more challenging in the two remaining sectors. Perspectives of improvement regarding coverage and data quality are proposed.