The effects of labetalol were compared with those of placebo in a multicentre randomized double-blind and prospective study of 152 patients with mild to moderate, non-proteinuric pregnancy-induced hypertension. Labetalol in a dose of 100 mg three times daily, increasing to 200 mg three times daily where required, significantly reduced maternal mean arterial pressure. There was some reduction in preterm delivery, neonatal respiratory distress syndrome and jaundice in the labetalol-treated group. Intrauterine growth retardation and neonatal hypoglycaemia occurred with the same frequency in both groups. There were no perinatal deaths. Labetalol appears to be an effective agent in the management of mild to moderate pregnancy-induced hypertension. The data from this study suggest possible advantages and no apparent disadvantages for the fetus during its use.