IMPORTANCE: Only about half of patients with high blood pressure (BP) in the United States have their BP controlled. Practical, robust, and sustainable models are needed to improve BP control in patients with uncontrolled hypertension. OBJECTIVES: To determine whether an intervention combining home BP telemonitoring with pharmacist case management improves BP control compared with usual care and to determine whether BP control is maintained after the intervention is stopped. DESIGN, SETTING, AND PATIENTS: A cluster randomized clinical trial of 450 adults with uncontrolled BP recruited from 14,692 patients with electronic medical records across 16 primary care clinics in an integrated health system in Minneapolis-St Paul, Minnesota, with 12 months of intervention and 6 months of postintervention follow-up. INTERVENTIONS: Eight clinics were randomized to provide usual care to patients (n = 222) and 8 clinics were randomized to provide a telemonitoring intervention (n = 228). Intervention patients received home BP telemonitors and transmitted BP data to pharmacists who adjusted antihypertensive therapy accordingly. MAIN OUTCOMES AND MEASURES: Control of systolic BP to less than 140 mm Hg and diastolic BP to less than 90 mm Hg (<130/80 mm Hg in patients with diabetes or chronic kidney disease) at 6 and 12 months. Secondary outcomes were change in BP, patient satisfaction, and BP control at 18 months (6 months after intervention stopped). RESULTS: At baseline, enrollees were 45% women, 82% white, mean (SD) age was 61.1 (12.0) years, and mean systolic BP was 148 mm Hg and diastolic BP was 85 mm Hg. Blood pressure was controlled at both 6 and 12 months in 57.2% (95% CI, 44.8% to 68.7%) of patients in the telemonitoring intervention group vs 30.0% (95% CI, 23.2% to 37.8%) of patients in the usual care group (P = .001). At 18 months (6 months of postintervention follow-up), BP was controlled in 71.8% (95% CI, 65.0% to 77.8%) of patients in the telemonitoring intervention group vs 57.1% (95% CI, 51.5% to 62.6%) of patients in the usual care group (P = .003). Compared with the usual care group, systolic BP decreased more from baseline among patients in the telemonitoring intervention group at 6 months (-10.7 mm Hg [95% CI, -14.3 to -7.3 mm Hg]; P<.001), at 12 months (-9.7 mm Hg [95% CI, -13.4 to -6.0 mm Hg]; P<.001), and at 18 months (-6.6 mm Hg [95% CI, -10.7 to -2.5 mm Hg]; P = .004). Compared with the usual care group, diastolic BP decreased more from baseline among patients in the telemonitoring intervention group at 6 months (-6.0 mm Hg [95% CI, -8.6 to -3.4 mm Hg]; P<.001), at 12 months (-5.1 mm Hg [95% CI, -7.4 to -2.8 mm Hg]; P<.001), and at 18 months (-3.0 mm Hg [95% CI, -6.3 to 0.3 mm Hg]; P = .07). CONCLUSIONS AND RELEVANCE: Home BP telemonitoring and pharmacist case management achieved better BP control compared with usual care during 12 months of intervention that persisted during 6 months of postintervention follow-up. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00781365.