We conducted a 14-day survey of the emergency department (ED) at a university tertiary care teaching hospital to examine appropriate and inappropriate use of the ED. The results are based on a convenience sample of 849 patients, selected to represent a 1-week period. Three categories (CAT) of patients were defined. CAT I: patients had a medical condition that could only be assessed in the ED. CAT II: patients had a medical condition that required evaluation either in the ED or elsewhere within 6 hours of triage. CAT III: patients could wait to be evaluated 6 or more hours from time of triage. Patients in CAT II were matched with outpatient facilities (OPF), based on the time of presentation, the presenting complaint, investigative tests, and treatments required. Overall, it was found that 69% of the patients were appropriate users and could have been seen only in the ED. Fifteen percent of the patients were classified as inappropriate users and should have been seen at an OPF. The remaining 15.8% represented "gray zone" cases. An interview conducted on a subset of ambulatory patients revealed the main reasons for choosing to visit the ED were lack of awareness of other facilities, perceived seriousness of condition, trust in the ED staff, or proximity of the ED. It was concluded that misusers represent a small portion of our ED caseload.