1. Six patients with borderline hypertension underwent training in exteroceptive biofeedback (BFB) in order to increase or decrease arterial pressure.
2. Systemic haemodynamics, intravascular volume and peripheral renin activity were determined before, during and after training sessions.
3. BFB training resulted in a significant reduction in mean arterial pressure (from 116 ± 4·6 to 101 ± 2·5 mmHg) mediated through a fall in total peripheral resistance; cardiac output, heart rate, intravascular volume and plasma renin activity remained unchanged.
4. In contrast, the increase or decrease of arterial pressure that occurred during BFB training was produced predominantly through changes in cardiac output and heart rate respectively, whereas total peripheral resistance under these circumstances remained unaffected.
5. The haemodynamic effects of BFB seem remarkably similar to the immediate or chronic effects of β-adrenoreceptor blockade, initially producing a fall in cardiac output followed by a reduced arterial pressure associated with a decreased total peripheral resistance.