Objectives: Prolonged stays in an emergency department (ED) are an important factor in ED crowding. This study compared characteristics of patients with different dispositions from an ED.Methods: This was a cross-sectional study design. The sample was composed of selected patients who visited the ED at a medical center in southern Taiwan in 2008. Data were collected from the computer-based information system.Results: A total of 24,322(28.9%) patients stayed in the ED for over 6 hours. Of those patients, 52.1%, (n =12,670), were male, 18.6% (n = 4524) were aged 75 or over, 46.8% (n = 11,380) were in triage category 3, 61.7% (n = 15,008) were medical patients, and 39.3% (n =9,548) were admitted during the day shift. Among these patients who stayed more than 6 hours, gender, age, and triage category were found to be significantly different between ”may be discharged” and ”hospitalize” dispositions. Approximately 10% had unscheduled returns to the ED within 3 days after ”may be discharged” and 85.7% of those returns were associated with the same diagnosis as on the previous visits. There was a signification correlation (r =0.221, p＜0.05) between the number of ED visits and stays over 6 hours.Conclusions: The study results indicated that patients who stayed in the ED for more than 6 hours had high percentages of hospitalization (50%) and readmission (30%). If these patients could be identified and hospitalized sooner, then they would spend less time in the ED. Appropriated admission policies and required patient education and monitoring might also decrease ED crowding.