Walk-in clinics have proliferated rapidly in many areas of Canada and the United States. Patients who attend these clinics have illnesses that are similar to those seen in family physicians' offices, yet walk-in patients perceive their symptoms to be more urgent and present at a much earlier stage of their illness than patients who attend their family doctor. Research has not yet proven that the opening of walk-in facilities lowers the demand for traditional primary care services; therefore the cost-effectiveness of walk-in clinics needs further evaluation.