Objective: To characterize the ED utilization patterns of the elderly population using nationally representative data. Methods: A secondary analysis was performed using the National Hospital Ambulatory Medical Care Survey (NHAMCS), a nationwide, stratified probability sample of ED encounters. Using these physician-reported data, the demographics, patient complaints, physician diagnoses, and dispositions were compared by age group, i.e., young-old (age 65-84 years) vs old-old (age greater than or equal to 85 years). Results: The elderly (age greater than or equal to 65 years) represented 5,038 (19.6%) of 25,646 ED encounters for all adults (age greater than or equal to 18 years). The geriatric age groups (ages 65-74, 75-84, and greater than or equal to 85 years) accounted for 45.3%, 37.4%, and 17.2% of all the encounters by the elderly. The proportions of female patients and white patients were higher with increasing age, The proportion of elderly patients hospitalized was 4 times that of younger adults and reflected monotonic increase with increasing age among elders, Patient complaints and physician diagnoses were generally similar for the young-old (65-84 years) and the old-old (greater than or equal to 85 years). Conclusions: These findings are consistent with previous single-center studies of geriatric ED patients. This data source may be useful for investigation of clinical issues related to the care of elderly ED patients.