Fenoldopam, a selective agonist of dopamine-1 receptors, is a regional and systemic vasodilator. In randomized, controlled clinical trials, fenoldopam has been found to preserve renal function in situations of potential renal ischemia, such as during radiocontrast administration, cardiac and peripheral vascular surgery, liver transplantation, and treatment of severe hypertension. Fenoldopam lowers blood pressure in patients with hypertension, but has little or no effect on blood pressure in those who are normotensive. The role of fenoldopam in managing critically ill, transplant, and hypertensive patients is reviewed in this article.