Physicians often face the problem that they have to treat anxiety and insomnia in patients who are dependent on narcotics or other substances. Reports about different reinforcing properties of different benzodiazepines and increasing concern about their misuse, often in combination with other drugs, call for studies that help to establish recommendations for choosing psychopharmacologic agents in the treatment of these patients. Opiate addicts enrolled in a methadone maintenance program were interviewed about their subjective "liking" of all psychotropic substances with which they had personal experience. The results confirm previous reports that certain benzodiazepines, especially flunitrazepam and diazepam, stand out from others in terms of positive reinforcing properties. Overall, the attractiveness of benzodiazepines as drugs of abuse for poly-drug abusers is lower than that of other sedative/hypnotics.