Forty-eight elderly patients with uncomplicated mild essential hypertension entered two drug regimens. In group 1, clonidine monotherapy (n = 15), clonidine was titrated to achieve goal blood pressure (less than 90 mm Hg diastolic) in dosages of 0.05 mg twice daily to 0.2 mg three times daily. Blood pressure decreased without major side effects (p less than 0.001). Three patients required small doses of diuretic after six months of clonidine monotherapy. In group 2, step-care therapy (n = 33), clonidine was added to chlorthalidone, 25 mg daily, for three weeks. Eight patients achieved the goal blood pressure with chlorthalidone, 25 required clonidine (0.1 mg to 0.3 mg twice daily) to achieve blood pressure control. Side effects of clonidine did not require discontinuation of therapy. Retrospective analysis of up to 2 1/2 years of clonidine plus diuretic (n = 51) showed a similar blood pressure reduction. Clonidine can be used effectively with or without a diuretic in the elderly hypertensive.