Resistant hypertension has become a less frequently encountered clinical problem. It may be defined as failure to control pressure below levels of 160/100 mm Hg despite adequate nonpharmacological intervention and pharmacotherapy. Adequate therapy is defined as the use of three antihypertensive agents, which includes a diuretic plus two other compounds. Resistant hypertension may be classified as physician resistant, patient resistant, and hypertension resistant. Each of these categories is described, and resolution of the problem of resistance can usually be achieved by improved patient education and adherence to therapy, reevaluation of diagnosis, and consideration of alternative therapeutic programs.