Objectives: The objectives of this study are to estimate the number of people seeking treatment on an annual basis in Ontario at specialized problem gambling treatment programs and describe important characteristics of clients. Method: Agency staff prospectively collected four broad information categories from clients: demographics, gambling activities, problem severity and services received, and submitted the data to a central database. Sample: The report includes submissions (total caseload equals 2224) from 44 designated problem gambling programs between January 1, 1998 and April 30, 2000. Results: Of the 2224 clients in treatment, 1625 (73.5%) were seeking help for their own gambling problem, and 504 (22.8%) were seeking help in dealing with a family member/significant other's gambling problem. The overall gender ratio of cases in treatment was about 1.4:1 (58.3% to 41.7%) males to females. A wide range of gambling activities was reported as problematic. Conclusion: Only a small percentage of people experiencing problems related to gambling are seeking help from specialized treatment programs. Population survey data are needed in Ontario to assess the potential over- or under- representation of particular sub-groups in treatment compared to the epidemiology of problem gambling in the community.