Four cohorts of patients entering a psychiatric case-register for the first time from 1974 to 1977 were each followed for a period of one year. Patterns of care were studied and related to characteristics of patients and services. Consequences for planning were discussed for three major categories: the aged, adults and youth, because they have each their own network of services. The most important high risk group appears that of single, divorced or widowed adult and aged patients. In this study youngsters, except for young married girls, run a lower than average risks of contacting a mental health service.