For the emergency patients in need of immediate resuscitation, cardiac catherization along with intensive cardiac monitoring is necessary to evaluate the cardiovascular stability. But this method requires machinery, technique and time which limits its use in emergency situations. In 1961, Allgower and Buri first discribed shock index, heart rate divide by systolic blood pres- sure, as easy to calculate and easy to use in acute settings given the simple measurements of the heart, rate and the blood pressure. It has been said in circulatory failure patients shock index is inversely related to left ventricular stroke work. Because shock index is an indicator for resuscitation and also a prognostic indicator it could be applied in triaging an emerency patients. Therefore we studied the significance and the possible triage application of shock index in emergency patients. In the period of 6 months from May 1 to October 31, 1994. Among total 15,782 patients, who visited Yonsei University-affliated Yong Dong Emergency Department, 2425 patients were included in the study. There were 201 admissions to the intensive care unit and 2105 patients to general beds and 119 selected patient from discharged. Retrospective chart review for pulse rate, systolic blood pressure, diastolic pressure and shock index was done. Statistical analysis was performed using t-test, p value of less than 0.05 was designated significant. Average shock index for ICU patients were 0.96+-0.50, general ward admittees were 0.67+- 0.18, and discharged were 0.65+0.16. There were significant statistical difference in shock indices between ICU and general ward patients, and ICU and discharged patients. Shock index is helpful in identifing patients with potential for admission to the ICU in emergency situations. Therefore we conclude that the shock index should be recognized as a triage tool.