It is not established whether behavioral interventions add benefit to pharmacological therapy for hypertension. We hypothesized that behavioral neurocardiac training (BNT) with heart rate variability biofeedback would reduce blood pressure further by modifying vagal heart rate modulation during reactivity and recovery from standardized cognitive tasks (“mental stress”). This randomized, controlled trial enrolled 65 patients with uncomplicated hypertension to BNT or active control (autogenic relaxation), with six 1-hour sessions over 2 months with home practice. Outcomes were analyzed with linear mixed models that adjusted for antihypertensive drugs. BNT reduced daytime and 24-hour systolic blood pressures (−2.4±0.9 mm Hg,
P=0.009, and −2.1±0.9 mm Hg, P=0.03, respectively) and pulse pressures (−1.7±0.6 mm Hg, P=0.004, and −1.4±0.6 mm Hg, P=0.02, respectively). No effect was observed for controls ( P>0.10 for all indices). BNT also increased RR-high-frequency power (0.15 to 0.40 Hz; P=0.01) and RR interval ( P<0.001) during cognitive tasks. Among controls, high-frequency power was unchanged ( P=0.29), and RR interval decreased ( P=0.03). Neither intervention altered spontaneous baroreflex sensitivity ( P>0.10). In contrast to relaxation therapy, BNT with heart rate variability biofeedback modestly lowers ambulatory blood pressure during wakefulness, and it augments tonic vagal heart rate modulation. It is unknown whether efficacy of this treatment can be improved with biofeedback of baroreflex gain. BNT, alone or as an adjunct to drug therapy, may represent a promising new intervention for hypertension.