Inappropriate use or misuse of EMS (Emergency Medical Service) is a potential waste of resources and diversion of needed service from another in need. One of the most serious consequences of an inappropriate use of EMS is emergency department (ED) overcrowding. ED overcrowding in large hospitals, especially university hospitals, has been a persistent and unsolvable problem worldwide. The issues have drawn the attention of media and have been discussed in many conferences. Currently, various studies have identified the causes and suggested the solutions for these problems. The inappropriate use of EMS are mainly caused by the misguidance of EMS providers and misuse of the public user. In order to solve this problem, the EMS system provider should make an effort to improve and develop the system. The government will also need to step up publicity activity on the awareness for an appropriate use of EMS system through mass media. ED overcrowding are caused by misuse of both EMS and medical transfer system. And inefficiency of hospital operating system is another cause. The hospital and its ED have to respond more rapidly to eliminate the unnecessary wait time of ED patients. Relocation of boarding ED patient to other inpatients area, such as hallways, conference rooms, is the first thing to do. To improve the flow of ED patients, the persons in charge of every department will have to come together to coordinate the early discharge of hospital patients and the scheduling of elective and surgical patients. The suggested solutions must be put in practice immediately.