This study's purpose was to identify risk factors for return and admission within 72 hours of discharge from the emergency department (ED). During a 2-year period, 104,584 patients were seen and discharged in the ED, and 493 (0.47%) patients returned within 72 hours requiring admission. Risk factors compared were age, sex, race, insurance status, and initial diagnosis. Initial visits were also characterized by weekday, means of arrival, time of arrival and discharge, and time between visits. Older patients, especially over 65 years, and patients with insurance for the elderly (Medicare) were at higher risk. The highest risk initial diagnosis categories were mental disorder (1.2%), genitourinary system (0.93%), and symptom-based diagnoses (0.76%). Also, a high proportion of patients arrived by ambulance. Patients at increased risk of early admission can be identified and should be the first target for prospective prevention strategies that seek to minimize high-risk early returns to the ED.