1. The results of a clinical trial of practolol in sixty-one patients with moderate and severe hypertension are presented. Alone or with a diuretic the drug was highly effective in thirty patients, and in a further eight who developed side effects. Effectiveness was not directly related to dosage or blood levels of drug, or to the severity of the hypertension.
2. Nine non-responders to practolol were found to respond to propranolol which is probably a more widely effective antihypertensive agent. Nevertheless, the additional safety factors of practolol and twice daily dosing make it first choice for many patients. We have been impressed by the ability of both β-blocking drugs to control blood pressure without impairing the quality of every-day life.