Hertfordshire1 The effects on heart rate, blood pressure and pulmonary function of single oral doses of prizidilol hydrochloride (400 mg SK&F 92657) and propranolol (40 mg) were compared with placebo in nine healthy volunteers, in a double blind crossover study. 2 Prizidilol had no effect on heart rate while propranolol caused a significant reduction compared with placebo. Diastolic blood pressure was lowered to the same extent by both prizidilol and propranolol.3 Propranolol significantly reduced the forced expiratory volume in 1 second (FEVy), forced vital capacity (FVC) and the maximal expiratory flow at 50% vital capacity (MEF 50). Prizidilol had no effect on flow-volume loop parameters. 4 Effective pulmonary blood flow was not altered by propranolol, but it was significantly increased by prizidilol. 5 Oral prizidilol exerts its hypotensive effect by vasodilatation without reflex tachycardia. It does not cause airways obstruction in healthy subjects.