Purpose: The declining recruitment rate of pediatric residents in Korea has led to a decrease in the number of emergency departments (EDs) offering a 24/7 pediatric emergency care (PEC). This study evaluated the impact of reduced PEC hours on the utilization patterns of a single ED.Methods: We reviewed medical records of pediatric patients who were defined as individuals aged 14 years or younger undergoing pediatricians’ practices in a tertiary hospital ED in Korea. Given the reduction of PEC hours from full-time to 08:00-24:00 on September 27, 2022, the patients were grouped as those who visited during March 27, 2022-September 26, 2022 (“control”), and those who visited during September 27, 2022-March 26, 2023 (“reduction”). The following variables were analyzed between the 2 periods: the number of patients, age, sex, visits via ambulances, severity by the Korean Triage and Acuity Scale with high acuity (a level 1-2 of the scale), disease-related visits, time of visit, ED length of stay (EDLOS), disposition, chief complaints, and diagnoses.Results: Among 3,577 pediatric patients, 1,315 visited the ED during the reduction period, down by 41.9% in numbers from the control period. From the control to reduction periods, we observed an increase in the median age (from 3.0 years [interquartile range, 1.0-7.0] to 4.0 years [1.0-8.0]; P = 0.005) and decreases in the median EDLOS (from 140.0 minutes [80.0-217.0] to 104.0 minutes [54.0-169.8]; P < 0.001) and proportion of hospitalization (from 22.1% to 12.6%; P < 0.001). No change was observed in the proportions of highacuity cases or chief complaints. We noted decreases in infection-related diagnoses during the reduction.Conclusion: Reducing PEC hours was associated with shorter EDLOS, fewer hospitalizations, and older age, with no difference in the severity. Even with reduced PEC hours, relevant resources should be redistributed to ensure the accessibility to PEC.