Objectives To compare thedifferent pattes of coronary artery calcification (CAC)in acute and chronic coronary syndromes utilizingelectron beam computed tomography. BackgroundPathologic, angiographic, and intracoronary ultrasoundstudies revealed sharp differences in the plaque mor-phology between patients with acute versus chroniccoronary syndromes. Whether there are different pat-tes of coronary artery calcification in patients withstable angina pectoris (SAP) and in those with unstableangina pectoris (UAP) or acute myocardial infarction(AMI), however, remains unclear. Methods Twohundred and sixty- four patients, including 67 withSAP, 94 with UAP and 103 with AMI were studied withelectron beam computed tomography for analysis ofcoronary artery calcification and with selective coronaryangiography for determination of atherosclerotic le-sions. CAC prevalence and calcium score were com-pared among three groups, and relation of CAC to theseverity of atherosclerotic disease in the SAP and UAPpatients was separately analyzed. Results Preva-lence of CAC was 100 % in the SAP patients, signifi-cantly higher than the 87.23 % in UAP patients and86.41% among the patients with AMI ( P ＜ 0.05) .More patients and arteries in the SAP group had severeforms of calcium than those in the UAP and AMI group(P ＜0.01), and the mean LN [CS+1 | (naturallogarithm transformation of calcium score) of the SAPpatients was much greater than that of the UAP andAMI patients ( P ＜ 0. 001 ). The distribution of vesselswith various CAC by luminal stenosis was different be-tween SAP and UAP patients. The average CAC extentof the infarct - related arteries was less severe than thatof the noninfarct - related arteries. Conclusions U-tilizing electron beam computed tomography, wedemonstrated that there exist different pattes of coro-nary artery calcification in patients with acute versuschronic coronary syndromes, which may provide insightinto the differences observed in the clinical and patho-logic development between these two types of coronaryartery disease.