Recent investigations of the complex interactions among vascular endothelium, platelets and leukocytes have relevance to the pathogenesis of atherosclerosis and ischemic heart disease. Perturbations in the hemodynamic equilibrium maintained by these cellular elements may lead to vasospasm, in vivo thrombosis and a reduction in blood flow. Recent advances in the understanding of these interactions in health and disease states are summarized. The effect of pharmacologic agents on these cell-cell interactions are discussed to provide the reader with a general understanding of the relevance of these interactions in cardiovascular disease.