Cardiac CT scanning, such as coronary artery calcium (CAC) scoring and multislice CT angiography (CTA), allows the direct visualization of coronary atherosclerosis. CT is a non-invasive test that provides information on stenosis severity and composition, as well as the cumulative burden of coronary plaques. The detection of subclinical coronary plaques is increasingly recognized as an important estimator of risk, with high, independent correlation to future adverse cardiac events. Both CAC scoring and CTA can be used clinically for cardiovascular risk assessment and the investigation of chest-pain syndromes. For either of these indications, CT is most effective when applied to the majority of cardiac patients with intermediate cardiovascular risk. The effectiveness of CT is based on the likelihood that CAC scoring and CTA will modify clinical decision-making in patients with different pre-test risk categories, and on the ability of CT to identify patients with hemodynamically relevant stenoses, as well as patients at high risk for future hard cardiovascular events (eg, cardiac death and non-fatal acute myocardial infarction).