The haemodynamic effects of oral and intravenous salbutamol were investigated in 22 patients with chronic heart failure. Intravenous salbutamol (13 micrograms/min) increased cardiac index by 53 per cent from 1.5 +/- 0.13 1/min per m2 to 2.3 +/- 0.23 1/min per m2 and decreased systemic vascular resistance by 28 per cent from 29.4 +/- 3.9 units to 21.2 +/- 2.5 units. Heart rate rose by 10 per cent from 101 +/- 3.5 beats per minute to 111 +/- 3.2 beats per minute and pulmonary artery end-diastolic pressure fell by 13 per cent from 26.3 +/- 1.8 mmHg to 22.8 +/- 2.1 mmHg. Similar results were obtained after oral salbutamol (8 mg). Cardiac index rose by 40 per cent and systemic vascular resistance fell by 30 per cent. There was a small rise in heart rate and a variable and not significant change in pulmonary artery end-diastolic pressure. Experiments on isolated rabbit papillary muscle showed that salbutamol, at the concentration which exists in patients, had no detectable positive inotropic effect. It is probable that the increase in cardiac output in patients is primarily the result of reduced afterload caused by vasodilatation. Salbutamol is a useful drug in the treatment of chronic heart failure.