OBJECTIVE: To describe the prevalence of continuity of care over a 5-year period in a complete cohort of urban children universally insured for medical care provided under fee-for-service reimbursement. METHOD: All children enrolled in the study were born to women living in metropolitan Winnipeg between July 1, 1987 and December 31, 1988 (N = 12,590). All ambulatory physician services for this group were enumerated from computerized administrative databases for the period from birth through 60 months. Continuity of care, defined as the proportion of total care provided by the most frequently seen physician or physician practice over time, was calculated for each child. Descriptive analyses include an examination of maternal and household characteristics associated with children receiving 80% or more of total ambulatory care from a single provider source. RESULTS: From birth to 24 months, 51% of children received at least 80% of ambulatory visits from a single provider practice. This proportion of the children declined to 28% at 25 through 60 months. Children living in low-income neighborhoods had poorer continuity profiles. Other household factors associated with poor continuity included young maternal age, single maternal marital status, residential mobility, and inadequate maternal use of prenatal medical care. Households affiliated with pediatric practices had better continuity profiles than households affiliated with general medical practices. CONCLUSION: Despite universal medical insurance, barriers to a longitudinally continuous relationship with a primary care provider remain in this setting. Although this study has emphasized the description of those barriers associated with household characteristics, there is evidence that factors related to the organization and delivery of medical care are also relevant.