A retrospective study is presented of the effect of propranolol on fetal outcome in pregnancies complicated by maternal hypertension. In nine pregnancies in which propranolol was given to markedly hypertensive women (diastolic blood pressure over 105 mm Hg) the fetal outcome was worse than in 15 patients using other hypotensive agents. The probability of fetal or neonatal death was related to the amount of proteinuria and the presence of parenchymal renal disease but was also significantly higher when the mother had been treated with propranolol. Experimental evidence suggests that beta-adrenergic blockade is harmful to the hypoxic fetus, for these reasons the use of propranolol in hypertensive pregnancies complicated by placental insufficiency may be contraindicated unless there is no satisfactory alternative.