Reductions in health care funding by both the federal and provincial governments in recent years have focused attention on the cost-effectiveness of health care delivery, particularly on the delivery of primary care services. We use data extracted from the Ontario Health Insurance Plan (OHIP) claims database to assess differences between walk-in clinics and other primary care delivery settings in initial visit costs, follow-up visit costs, service duplication, and diagnoses treated. Our analysis indicates that the generally negative reputation of walk-in clinics is largely underserved. Walk-in clinics differ very little from office-based practices in terms of overall costs, the percentage of patients seen again, and follow-up costs. The relatively high costs of primary care provided in emergency departments combined with the fact that a fairly large share of visits to emergency departments are for self-limiting conditions suggest that patient education on the proper use of emergency departments or providing alternatives, such as telephone triage services, should result in health care cost savings.