Two maintenance drugs had been used in France since 1996, methadone and high-dosage buprenorphine. This study aimed to examine changes in drug use from observations gathered between 1995 and 1997, within the framework of the French program for the monitoring of drug dependence (OPPIDUM). This annual survey studies psychoactive substances consumed by drug addicts attending specialised drug care centres. During the last three surveys, 16 centres collected a total of 1597 patient-files. This study shows an increase in the number of patients undergoing maintenance treatment (from 14 to 69%), a reduction in the number of intravenous drug users (from 55 to 22%) and a reduction in consumption of psychoactive substances. However, poly-drug addiction behaviour continues and high-dose buprenorphine subjects frequently use the substance intravenously and in association with benzodiazepines.