The purpose of the study was to determine how children's use of primary health care services was related to family resources (socio-economic status, marital and residential stability of the family, and core/periphery dichotomy). The population consisted of a random sample of 3201 children from 15 municipalities in the province of Uudenmaan lääni in Southern Finland in 1979. Among two-parent families in the core regions total utilization of primary health care services was significantly higher among the children of workers and upper white-collar employees. Children of farmers and lower white-collar employees in the periphery exhibited low primary health care utilization. Children in upper white-collar employees' families (both two- and one-parent) in core regions frequently used private services. Among children of one-parent families, exceptionally high users of private services were children of upper white-collar mothers in core regions, and of municipal health services the children of working-class mothers in the periphery. Non-migrated children had a slight tendency to use health services more than migrated children. Differences in family resources thus cannot be ignored when children's utilization of primary health care services is studied.