We studied the six-month prevalence of four child psychiatric disorders (conduct disorder, hyperactivity, emotional disorder, and somatization) and patterns of service utilization for mental health and social services, ambulatory medical care and special education by different regions of Ontario, urban-rural residence, and age and sex groupings. Among children 4 to 16 years of age, the overall six-month prevalence rate of one or more of these disorders was 18.1%. The prevalences of hyperactivity and one or more disorders were significantly higher in urban areas than rural areas. The utilization data indicated that children with these psychiatric disorders, compared with children without these disorders, were almost four times more likely to have received mental health or social services in the six months preceding this study. However, five of six of these children had not received these specialized services in the previous six-month period. Over 50% of the children in the province had received ambulatory medical care in the last six months. Over 15% of the children in the province had received special education services at some time thus far in their school careers. Implications of these findings, especially for the provision of child mental health services, are discussed.