Aim To investigate the quantitative correlation between coronary calcium score (CS) determined by electron beam computed tomography (EBCT) and angiographically atherosclerotic plaque burden. Methods In 320 patients who were clinically suspected to have coronary artery disease and had undergone coronary angiography, EBCT was performed for calculating calcium score. The relation of calcium score to atherosclerotic plaque burden was quantitatively analyzed. Results The calcium score ranged from 0 to 3 346, with a median of 45. The mean natural logarithm transformation of calcium score ) was 3.64±2.18. LN(CS+1) was poorly related to stenosis severity (r=0.385, p<0.001) and well related to the total score of plaque burden (r=0.768, p<0.001). Conclusion Calcium score determined by electron beam computed tomography correlates intimately with plaque burden but poorly with stenosis severity.