The usefulness of captopril in managing hypertensive emergencies was evaluated in 9 untreated patients. During the 30 minutes following oral administration of 25 mg of this angiotensin converting enzyme inhibitor, blood pressure decreased from 239/134 to 204/118 mm Hg (p less than 0.05). At that time, furosemide (20 mg i.v. or 40 mg orally) had to be added in 5 patients to further decrease pressure levels. Ninety to 120 minutes after starting therapy, an additional dose of captopril (100 mg orally) was given to all patients. 12 and 24 hours after admission respectively, blood pressure averaged 140/93 and 139/86 mm Hg in the patients treated with captopril alone and 166/107 and 153/91 mm Hg in those treated with both captopril and furosemide. The blood pressure fall was well tolerated and no adverse effect was induced by captopril. These results show that captopril given alone or in association with a diuretic makes it possible to deal quickly and effectively with hypertensive crises without necessarily requiring monitoring in an intensive care unit.