Background : Acute respiratory infection, particularly pneumonia, is the most common cause of hospitalization and death during childhood in developing countries. This study was performed to investigate the characteristics of children and adolescents with pneumonia who visited emergency rooms(ERs) in Korea. Methods : We analyzed the National Emergency Department Information System (NEDIS) records of 139 ERs in Korea of all pediatric patients aged under 18 years with pneumonia during one year (Jan to Dec 2012). Results : A total of 26,557 subject were found and the male to female ratio was 1.0:0.81. Patients aged under 12 months was 21.1%, aged 1 to 3 years was 57.5%, aged 4 to 6 years was 13.4%, aged 7 to 12 years was 5.3%, and aged 13 to 18 years was 2.7%. The attending rate was also high in January, April, May, and November. The outcomes of their ER visits, 55.5% of patients were hospitalized, 0.5% were transferred to other hospital. Among those hospitalized, 2.8% were admitted to the intensive care unit. The mortality rate was 0.02%. The cause of pneumonia as mentioned ICD-10 diagnostic code, viral pneumonia including influenza was 9.2%, mycoplasma pneumonia was 5.3%, bacterial pneumonia was 1.7%, and pneumonia of unknown origin was 83.8%. Conclusions : The results of this study showed that most of patients who visited to ER due to pneumonia was children of young age and half of those were admitted to hospital. The mortality rate was remarkably low. We guessed that seasonal patterns of ER visits for pneumonia may be related to seasonality of respiratory viruses.