Coronary calcium scoring is increasingly used as a screening test for coronary artery disease. Widespread agreement exists that coronary artery calcium (CAC) is a population marker for intimal atherosclerosis, However, the numerical significance of an individual's calcium score and what impact that score should have on future patient management is subject to disagreement. Questions also exist with regard to the interpretation of serial changes in CAC score. The answers to these questions heavily depend on an accurate and reproducible method of quantifying CAC. The purpose of this article is to review the alogrithms and techniques used in CAC quantification, and to identify those variables that may significantly affect its derivation.