In a mail survey of staff of specialized addiction treatment services in Ontario, respondents from different types of services varied in their level of support for a variety of harm reduction initiatives. Across all types of services support was common for needle exchange services (82-95% in favour) and for short-term non-abstinence goals for clients with alcohol or drug problems (51-98% in favour). However, mean ratings for the effectiveness of methadone maintenance were negative or near zero, and only in assessment/referral and out-patient samples did the majority (61% in each case) have a positive view of methadone maintenance programmes. Only a minority of respondents (15% to 35%) indicated support for the prescription of heroin to heroin addicts. In multivariate analyses, support for harm-reduction strategies was found to be positively related to belief in the effectiveness of pharmacological and cognitive-behavioural interventions and working in an out-patient treatment service, and negatively related to belief in interventions based on the disease model.