The Substitution Treatment National Registry provided from mid 2006 till mid 2009 an exhaustive documentation on all patients being prescribed methadone or buprenorphine in Belgium. This endeavour was possible through cooperation of all community pharmacies and their representative organizations was supported at the time by the former Health federal minister. The Liberal belgian opiate medical substitution process authorizes untill now de facto any doctor to prescribe methadone and pharmacists are supported to dispense it. Results show the regional, provincial and county numbers of professionals and patients prevalence in the population. Nationwide, n = 16974 patients (prevalence for population aged 20-64: 26/10000) have been offered substitution from mid 2008 till mid 2009, n = 3390 pharmacies 164,4% of all pharmacies) and n = 2937 MDs (16,75% of all MDs) have been involved. Subutex or Suboxone have been dispensed to 11,1% of substitution patients with 7,4% receiving only buprenorphine on a yearly basis. Number of substitution patients by MD and prevalence by gender, age group and region are presented. Important variations are observed locally, possibly mirroring heroin addiction due to widespread access to substitution treatment. Younger patients are more prevalent in semi rural or border areas. The exhaustivity of available data enables also to observe patients quitting substitution altogether and a strong difference of maintenance rate is observed favoring methadone over buprenorphine.