Background/Aims: Early evaluations of patients presenting with acute chest pain remain difficult. We examined the diagnostic capacity of multidetector computed tomography (MDCT) for acute coronary syndrome (ACS) in patients presenting with acute chest pain. Methods/Results: We examined 36 consecutive patients presenting with acute chest pain with neither diagnostic ECG changes nor elevated biomarkers. 64-slice MDCT was performed, and we evaluated the presenceof significant coronaryartery stenosis (>50% reduction in lumen diameter). Significant stenosis was detected in 15 patients by MDCT. Among them, 11 patients were diagnosed as having ACS based on the findings of coronary angiography or myocardial perfusion single photon emission computed tomography (positive predictive value 73%). All 21 patients without significant stenosis by MDCT, except only one, were regarded as not having ACS (negative predictive value 95%). Sensitivity and specificity were 92 and 83%, respectively. In patients without a history of coronary artery disease (CAD), both the specificity and positive predictive value improved to 100% (sensitivity 90%; negative predictive value 95%). In patients with neither a history of CAD nor coronary calcification, the diagnostic accuracy of MDCT was 100%. Conclusions: MDCT has high diagnostic capacity for the early evaluation of ACS, especially in patients without a history of CAD or coronary calcification.