The objective of this study was to determine whether a hypertension management program in which patients monitor their own blood pressure (BP) at home can reduce costs without compromising BP control. The prospective, randomized, controlled 1-year clinical trial was conducted at four medical centers of the Kaiser Permanente Medical Care Program in the San Francisco Bay Area. Of 467 patients with uncomplicated hypertension who were referred by their physicians, 37 declined to participate in the study; 215 were randomly assigned to a Usual Care (UC) group and 215 to a Home BP group. Twenty-five UC patients and 15 Home BP patients did not return for year-end BP measurements. Patients in the UC group were referred back to their physicians. Patients in the Home BP group were trained to measure their own BP and return the readings by mail. Patients were given a standard procedure to follow in case of unusually high or low BP readings at home. The number and type of outpatient medical services used were obtained from patient medical records for the study year and the prior year. Costs of care for hypertension were calculated by assigning relative value units to each outpatient service. Trained technicians measured each patient's BP at entry into the study and 1 year later. Home BP patients made 1.2 fewer hypertension-related office visits than UC patients during the study year (95% confidence interval (CI): 0.8, 1.7). Mean adjusted cost for physician visits, telephone calls, and laboratory tests associated with hypertension care was $88.76 per patient per year in the Home BP group, 29% less than in the UC group (95% CI: $16.11, $54.74). The annualized cost of implementing the home BP system was approximately $28 per patient during the study year and would currently be approximately $15. After 1 year, BP control in men in the Home BP group was better than in men in the UC group; BP control was equally good in women in both groups. Management of uncomplicated hypertension based on periodic home BP reports can achieve BP control with fewer physician visits, resulting in substantial cost savings.