The function of the vascular system is to transport oxygen and nutrients to the cells and to remove carbon dioxide and metabolites. It also transports hormones and locally produced neurohumoral substances which, in part, regulate its own function. These interrelationships are essential to homeostasis. The vascular system is not an assembly of simple (elastic) tubes but a dynamic system with many external and intrinsic regulatory mechanisms. The endothelium plays a major role in the intrinsic regulation of the system. The system is also often subject to disease processes of which atherosclerosis is the most important. As a result of atherosclerosis, and other disease processes, replacement of vessels with prosthetic devices may be required to reestablish adequate tissue blood flow. It is therefore imperative to gain insight into the details of vascular function, especially the dynamics, and the endothelium, the processes of atherosclerosis development, the vascular prosthetic possibilities and, last but not least, the interrelationships between these sub-specialties.