We report on the extent of cannabis treatment-seeking within an addiction treatment system in Canada. Data represent all new admissions in fiscal year 2000 to substance abuse treatment agencies in the province of Ontario (n = 47,995). Analyses examine the prevalence of cannabis problems by demographic and treatment characteristics and provide contrasts with other client subgroups (alcohol, cocaine, and opiates). Clients reporting cannabis as their primary problem substance (13%) were more likely to be male, single, under age 20 and in high school. Legal system involvement and school- or family-based pressure to enter treatment were commonly reported, but less so by older cannabis clients. The distinctiveness of these clients within the larger treatment system raises questions of the relevance to cannabis clients of interventions designed for other substance-abusing populations.