Background: Client characteristics provide useful information for designing programs that target individuals with risk factors for substance use and for determining client retention. Therefore, this study examined the profiles of clients attending a methadone clinic. Methods: A cross-sectional analysis of clients of a methadone clinic was conducted through a survey to obtain a profile of methadone clients. Results: Of the 51 patients who responded (response rate: 66.2%), the mean (SD) age at which they started substance use was 19.8 (5.1) years. Friends were cited as the most regular source of drugs (82.4%), and heroin was the most commonly used drug (98%). Daily substance use was reported by 72.5% of the respondents; 23.5% admitted to having stolen money to purchase drugs; 92.2% tried quitting substance use on their own and 98% stated that the main reason for registering at the clinic was that they wanted to stop their drug dependence. Approximately 60% of clients were receiving methadone doses of less than 60 mg/day. Conclusion: Heroin is still the most popular drug of abuse and most clients still receive methadone doses below the recommended level, despite evidence of poor patient retention rates associated with these low doses.