Matrix metalloproteases (MMPs) are responsible for the breakdown of extracellular matrix materials, including collagen and elastin. There is substantial evidence that, although the activity of MMPs in normal tissue is low, there is an increase in activity under a range of disease states that contributes to the chronic pathology of the disease. In cardiovascular disease, MMPs have been implicated in the development of ventricular remodelling post-infarction, and also in the degradation of the fibrous cap of atherosclerotic plaques, thereby contributing to plaque rupture. Recent attention has turned to using the presence of circulating MMPs in patients with recent acute myocardial infarction or unstable angina as a prognostic indicator for eventual chronic outcome. In addition, an emerging role for MMPs in contributing to the early consequences of acute myocardial infarction, such as cardiac dysfunction, has been identified.