Accurate risk assessment may be helpful in decreasing cardiovascular events through more appropriate targeting of preventive measures. Traditional risk assessment may be refined with the selective use of coronary artery calcium score (CACS) or other methods of subclinical atherosclerosis measurement. This article reviews information pertaining to the clinical use of CACS for assessing coronary atherosclerosis as a useful predictor of coronary artery disease (CAD) in certain population of patients. Coronary calcification is a marker of atherosclerosis that can be quantified with the use of cardiac CT and it is proportional to the extent and severity of atherosclerotic disease. The published studies demonstrate a high sensitivity of CACS for the presence of coronary artery disease but a much lower specificity for obstructive CAD depending on the magnitude of the CACS. Several large clinical trials have found clear, incremental predictive value of CACS over the Framingham risk score when used in asymptomatic patients. However, early detection of CAD by Electron Beam Tomography (EBT) screening has not convincingly demonstrated a reduction in mortality and morbidity. Nevertheless, relevant prognostic information obtained may be useful to initiate or intensify appropriate treatment strategies to slow the progression of existing atherosclerotic vascular disease. Current data suggest intermediate-risk patients may benefit most from further risk stratification with cardiac CT, as CAC testing is effective at identifying increased risk and in one study motivating effective behavioral changes. Randomized clinical trials will help determine if selective use of cardiac CT in the intermediate-risk patient would lead to more appropriate use of pharmacologic therapy and improved clinical outcomes.