Understanding the nature and role of endothelium-derived hyperpolarizing factor is crucial in the quest for improved treatments for hypertension, diabetes, ischemia-reperfusion, and other vascular disorders. EDHF 2002 is based on the proceedings of the Fourth International Symposium on endothelium-dependent hyperpolarizations. It will be of interest not only to physiologists and pharmacologists puzzled by the complexity of the interactions between the endothelium and underlying vascular smooth muscle cells, but also clinical researchers and physicians treating patients with cardiovascular diseases.