policy changes and the methadone maintenance treatment system for opioid dependence in ontario 1996 to 2001 background until recently the availability of methadone treatment in ontario canada was limited in 1996 policy changes were introduced to increase the availability of treatment the 5year impact of these policy changes is assessedmethods for these census data descriptive statistics were used to examine changes in the patient and provider populations over time using data from the college of physicians and surgeons of ontario methadone maintenance registry of patients and the registry of methadone prescribing physiciansresults between 1996 and 2001 the total number of clients in treatment increased substantially from 1595 to 7787 over this time period the number of physicians prescribing methadone increased from 60 to 161interpretation policy changes resulted in substantial increases in the patient and provider populations across ontario however the estimated low proportion of opiate users in treatment indicates that more efforts are needed to address the potential demand for treatment