Vascular remodeling is a general term describing any change in blood vessels structure caused by hemodynamic changes,such as flow and pressure,injury,or diseases. It also encompasses development and vascularity. This review focuses on the implications of remodeling from both structure and function of isolated arteries and on how a remodeled vascular bed responds to vasoactive stimuli. Essential, genetic, experimental, and pulmonary hypertension, endothelial dysfunction in atheroma, vascular surgery, subarachnoid hemorrhage, congestive heart failure, coronary col lateralization, ischemia, and pregnancy are among the examples discussed in this review. Research efforts should be directed toward understanding the processes of cell-cell interaction underpinning these changes in structure and function. Much could be gained from better measurement of vascular structure and full stimulus-reactivity relationships under in vivo conditions in a variety of vascular beds and models of animal and human hypertension. Mathematical models of the average vascular structure drawn from experimental data aid clear thinking when discussing the remodeling process.