Objectives To evaluate the health system cost of a home blood pressure monitoring (HBPM) program versus usual care in an integrated healthcare system. Study Design This cost-effectiveness analysis was based upon a previously completed randomized controlled trial of 348 hypertensive patients, in which mean systolic blood pressure (BP) was lowered 21 versus 8 mm Hg in the HBPM and usual care groups, respectively, and BP control was achieved in 54% versus 35% of patients (P < .001). Methods This analysis compared direct costs from the health plan perspective, including clinic visits, e-mail and telephone encounters, laboratory tests, medications, hospitalizations, and emergency department visits between the 2 groups. Primary outcomes were the incremental hypertension care-related cost of HBPM per mm Hg lowering of systolic BP per patient, per additional BP controlled, and per life-year gained. Results Median hypertension-related cost per patient over 6 months was $455 in the HBPM group and $179 for usual care (P < .001). This increase was attributable to additional e-mail and telephone encounters, greater antihypertensive medication use, additional laboratory monitoring, and the BP monitor. Median total cost per patient was $1530 and $1283 for the HBPM and usual care groups, respectively (P =.034). The HBPM program increased hypertension-related expenditures by $20.50 per mm Hg lowering of systolic BP, $1331 per additional patient achieving BP control at 6 months, and $3330 per life-year gained. Conclusions The HBPM program requires investment in outpatient encounters, medications, and laboratory monitoring, but produces significantly improved BP control.