OBJECTIVE: Under the overcrowding conditions of large emergency departments, the proportion of elderly patients is increasing in Korea. This paper describes the necessity of the preparedness of Korean emergency departments and society for the rapidly aging population. METHODS: This was a retrospective observational study. Patients who presented to a tertiary hospital emergency department (ED) in one year were included. The use of medical resources between young adult (≥20 and <65 years of age) and elderly patients (≥65 years of age) was compared. RESULTS: This study included 26,712 patients. The young adult group and the elderly group was 15,021 (56.2%) and 11,691 (43.8%), respectively. The ratio of firehouse ambulance visit mode (28.6%) and inter-facility transfer visit mode (18.9%) of the elderly group was higher compared to those of the young adult group (26.4% and 10.6%, P<0.001). The elderly group visited more at daytime (P<0.001). With aging, the admission ratios of the elderly group to the general ward (38.9%) and intensive care unit (13.0%) were higher than the young adult group (9.8% and 4.3%, P<0.001). The mean ED length of stay and mean length of hospitalization of the elderly group was longer than that of the young adult group (P<0.001). The medical cost of the elderly group was approximately three times higher than that of the young adult group. CONCLUSION Elderly patients required more emergency medical resources in both the prehospital and hospital stages. Korean emergency departments and society require efforts for not only expansion but also the appropriate use of medical resources in a rapidly aging population.