As aging progresses, clinical characteristics of elderly patients in the emergency department (ED) vary by age. We aimed to study differences among elderly patients in the ED by age group.For 2 years, patients aged 65 and older were enrolled in the study and classified into three groups: youngest-old, ages 65 to 74 years; middle-old, 75 to 84 years; and oldest-old, ≥85 years. Participants' sex, reason for ED visit, transfer from another hospital, results of treatment, type of admission, admission department and length of stay were recorded.During the study period, a total 64,287 patients visited the ED; 11,236 (17.5%) were aged 65 and older, of whom 14.4% were 85 and older. With increased age, the female ratio (51.5% vs. 54.9% vs. 69.1%, P<0.001), medical causes (79.5% vs. 81.3% vs. 81.7%, P=0.045), and admission rate (35.3% vs. 42.8% vs. 48.5%, P<0.001) increased. Admissions to internal medicine (57.5% vs. 59.3% vs. 64.7%, P<0.001) and orthopedic surgery (8.5% vs. 11.6% vs. 13.8%, P< 0.001) also increased. The ratio of admission to intensive care unit showed no statistical significance (P=0.545). Patients over age 85 years had longer stays in the ED (330.9 vs. 378.9 vs. 407.2 minutes, P<0.001), were discharged home less (84.4% vs. 78.9% vs. 71.5%, P<0.001), and died more frequently (6.3% vs. 10.4% vs. 13.0%, P<0.001).With increased age, the proportion of female patients and medical causes increased. Rates of admission and death increased with age and older patients had longer ED and hospital stays.