Patients die in the emergency department frequently; however, there has been little about the incidence and cause of Emergency Department death in the emergency medicine litersture. This study was conducted retrospectively to gain insight into the patients who die suddenly and unexpectedly in the Emergency Department,(ED). A total of 360 patients were prouounced dead in the ED frorn 1991 through 1994 in Chung Ang Gil Hospital. Of the 360 patients, 309 (86% ) were brought to the ED with cardiopulmonary resuscitation in progress or as do not resuscitation(DNR) patients, leaving 51(14%) patients who met the unexpected death criteria. Of the unexpected deaths, 32(62.7% ) patients presented to the ED with either abnormal vital sign (24 of 32) or some alteration in consciousness (18 of 32), or both of them (10 of 56). Medical and surgical causes of death represented 47.1% (24 patients) and 15.6% (8 patients) of the unexpected deaths respectively. Trauma represented 19 (37.3 %) of the unexpected deaths, with 14 of these being the result of motor vehicle collision. The yearly incidence of unexpected ED death is presented in numbers of deaths per 10,000 ED visits. In 1991, the incidence was 3.4, and in 1992, 1993 and 1994 those were 2.7, 2.2 and 2.1 respectively.