Little has been reported about Canadian walk-in clinics. The authors identified and surveyed 34 Ontario walk-in clinics in a preliminary descriptive study. A walk-in clinic was operationally defined as "a clinic that is separate from a hospital, has extended hours, and normally accepts patients without an appointment or a referral." Results showed that most Ontario walk-in clinics are not identifiable by name, have increased in number dramatically in the past two years, have laboratory, X-ray, and electrocardiographic facilities, and have varied practice patterns. Implications for rising health care costs and changing views on family practice were noted and suggestions made for future research.