OBJECTIVES: Diagnostic accuracy for coronary artery disease on dual source CT (DSCT) is slightly influenced by heart rate. The aim of this study is to evaluate diagnostic accuracy of DSCT by comparing the change of stenotic coronary artery diameter in diastole and systole according to heart rate (HR). METHODS: From Nov 2007 to Jan 2008, we studied 27 patients (13 men, 14 women; age, 46-78 years; mean age 63 years) who had coronary artery stenosis and were performed DSCT. Irrespective of the HR variability, no beta-blockers were given prior to scan. HR range was from 51 to 105 bpm (mean: 73 bpm). Diameter stenosis on DSCT was analyzed using workstation. Conventional coronary angiography (CAG) was used as standard of reference for evaluation of diagnostic accuracy of coronary artery stenosis on DSCT. We measured mean diameters of stenotic coronary arteries in systole and diastole according to HR, and correlated diagnostic accuracy with HR using linear regression analysis. RESULTS: Accuracy of diameter stenosis on DSCT was 94.1%. Mean difference of stenotic coronary artery diameter between diastole and systole was 12.9% in 50-59 bpm, 11.3% in 60-69 bpm, 10% in 70-79 bpm, 20% in 80-89 bpm, 13% in 90-99 bpm, 6.7% in 100-109 bpm. There was no statistical significance between diagnostic accuracy of coronary artery stenosis and HR. CONCLUSION: Diagnostic accuracy of coronary artery stenosis using DSCT was very high in spite of changing of diameter of stenotic vessels in systole and diastole according to HR.