Abstract The traditional income statements of emergency department cannot depict its overall financial contribution to a hospital. Therefore, this study is to calculate the potential earnings from an emergency patient being transferred to in-patient departments, and analyze the financial contribution, beyond the numbers in the income statements, of an emergency room to a hospital. This thesis adopts case study method by choosing the emergency rooms of two medical centers as samples, and investigates the earnings of other departments closely-related to the emergency rooms. Further, the emergency rooms’ potential influences on the overall operating evaluation and financial benefits to the hospital are also discussed. The results of the case study indicate that a substantial percentage of other departments’ in-patient revenues comes from those patients transferred from the emergency rooms. However, the financial figures in the monthly income statements of emergency rooms cannot show the important role the emergency room may play, resulting in underestimating the overall contributions of emergency rooms to the hospital on the basis of traditional income statements.