Background: High-mobility group box 1 protein (HMGB1) is a non-histone DNA-binding nuclear protein that has functions like pro-inflammatory cytokine. Recently,it has been suggested that HMGB1 detected in individuals with sepsis and hemorrhagic shock, was related to myocardial or cerebral ischemia.The aim of this study was to elucidate whether HMGB1 was a surrogate marker as a acute phase reactants for acute coronary syndrome(ACS). Subjects and Methods: We examined a total of 50 patients who underwent coronary angiogram due to chest pain or evidence of ischemic heart disease. According to clinical presentations, electrocardiographic findings, cardiac enzymes, coronary angiogram, the 50 patients were classified into the five groups; 1)normal (mean age=53짹11,M:F=4:6), 2)stable angina (mean age=66짹9,M:F=7:3), 3)unstable angina (mean age=61짹12,M:F=5:5), 4)non-ST elevation myocardial infarction (mean age=67짹10 years,M:F=5:5), 5)ST-elevation myocardial infarction (mean age=61짹13,M:F=5:5). ACS was defined as group 3 or 4 or 5. The serum levels of HMGB1 were measured by sandwich ELISA method. Results: The levels of HMGB1 in group 1,2,3,4 and 5 were significantly different [538짹146 ng/ml, 759짹179 ng/ml, 630짹201 ng/ml, 531짹115 ng/ml, 358짹229 ng/ml (p=0.001), respectively]. The level of HMGB1 in stable angina was higher than that in ACS (759짹179 ng/ml vs 506짹239 ng/ml, p=0.001). However, serum hsCRP level was significantly higher in ACS patients than in stable angina patients (12.7짹30.7mg/L vs 1.2짹0.8mg/L, p=0.002). The highest quartile of HMGB1 level in patients with coronary artery disease was significantly higher than normal subjects (864짹127 ng/ml vs 538짹145 ng/ml, median 552 ng/ml, p=0.001). Conclusion: The HMGB1 known as a mediator of systemic inflammation is related to chronic ischemic condition such as stable angina rather than acute inflammatory status such as ACS.