Coronary acute syndromes (CAD) are the result of atherosclerosis, a vascular disorder characterized by abnormalities in endothelial function, ultimately resulting to partial or complete vessel occlusion. Although recognized risk factors for CAD are helpful to predict the development of atherosclerosis, their ability to identify individual patients at risk of hard events is limited. In addition research has showed that excessive emphasis on the severity of coronary luminal stenosis may be misleading, and the majority of acute events occurs in patients with pre-existing noncritical arterial stenoses. Coronary calcium is intimately associated with coronary atherosclerotic plaque development, and may be used as surrogate marker to assessment the risk for an hard event in an individual subject. Coronary calcification is not a passive process of mineral precipitation but a biologically regulated phenomenon that has many similarities to bone formation. New imaging noninvasive methods, as electron beam computed tomography (EBCT), are able to identify, in asymptomatic patients, unstable coronary plaques that underline the clinical acute coronary syndromes. After a detailed description of the abovementioned context, clinical implications, diagnostic approaches and prospects for therapy of coronary calcifications are reviewed and discussed.