Slow infusions of diazoxide were administered to 10 hypertensive patients who had stable, nonaccelerated hypertension. The 10-min diazoxide infusion was associated with a 16% average reduction in arterial pressure, a 21% average increase in heart rate, a 16% average increase in cardiac output, and a 36% reduction in total peripheral resistance. These changes in hemodynamic parameters lasted for an average of 70 min. It was concluded that slow infusions of diazoxide produce a consistent and predictable antihypertensive effect in patients with stable, nonaccelerated hypertension. Slow infusions of diazoxide may have a limited use in nonemergency situations where an abrupt change in arterial pressure is to be avoided and a parenteral antihypertensive agent is needed.