Atherosclerotic plaques are composed of a lipid rich core, which is covered by a collagen rich fibrous cap. Rupture of the atherosclerotic plaque with superimposed thrombosis is the main cause of acute coronary syndromes, including acute myocardial infarction and unstable angina. The stability of the plaque depends on its collagen content; degradation of the collagen leads to a vulnerable plaque that is prone to rupture. Recent studies have demonstrated a critical role for matrix metalloproteinases (MMPs) in the degradation of the collagen content and the reduction of mechanical stability of the atherosclerotic plaques. Increased expression of various MMPs has been shown in the tissue sections of atherosclerotic plaques. The increased expression of MMPs in the atheroma also leads to increased MMP levels in the circulation. The cholesterol lowering drugs - 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) - decrease the tissue expression of various MMPs in atheromatous plaques by attenuating the inflammatory process that promotes MMP expression during the course of atherosclerosis. However, the effect of statin treatment on the serum levels of MMP-13, which has a critical role in the initiation of collagen degradation, is unknown. On the basis of these previous studies, we discuss the need for studies on the effect of statin treatment on the serum levels of MMP-13 and tissue inhibitor of matrix metalloproteinase (TIMP-1) levels in hypercholesterolemic patients.