Thirteen children (ages 9.2 +/- 3.7 years, mean +/- SD) received intravenous doses of labetalol, an alpha 1- and beta-adrenergic blocker, on 15 separate occasions for treatment of hypertension. In 12 of 15 episodes an initial dose of 0.55 +/- 0.34 mg/kg was given; in all 15 a continuous infusion of 0.78 +/- 0.39 mg/kg per hour was utilized for 67.3 +/- 57.1 hours. A significant decrease in systemic blood pressure occurred in all episodes (143/99.1 +/- 17.7/11.1 vs 115.6/72.4 +/- 7.7/9.5; p less than 0.01). A clinically unimportant yet statistically significant decrease in heart rate occurred during labetalol infusion (116.3 +/- 19.8 vs 107.8 +/- 11 beats/min; p less than 0.01). The episodes in children with creatinine clearances greater than 50 (n = 6) were compared with those with creatine clearances less than 20 ml/min per 1.73 m2 (n = 9); similar doses of labetalol were required for control of blood pressure. We conclude that infusion of labetalol is effective for control of blood pressure in children with hypertension, regardless of renal function.