To a large degree, modern antihypertensive therapy has evolved from the development of agents that act as vasodilators but, for one reason or another, avoid the disadvantages of the nonspecific vasodilators. This review examines the impact of antihypertensive agents on renal perfusion and function and relates it to their efficacy in reducing high blood pressure. Special attention is given to beta-adrenergic blocking agents that have a minimal impact on the kidney, converting enzyme inhibitors, calcium channel blockers and dopamine analogs. Also reviewed are the functional abnormalities involving the renal blood supply in essential hypertension, the role of newer pharmacologic agents in therapy and the nature and extent of reactive responses that often limit the response to therapeutic agents.