To The Editor.— The "Evaluation of Diazoxide (Hyperstat I.V.)" (224:1422, 1973) indicates that severe hypotension is rare when this agent is used. In our series of 140 injections of 300 mg of diazoxide given to 33 patients, four episodes of hypotension occurred. In each instance there was a fall in supine systolic blood pressure to less than 90 mm Hg and a decrease in mean blood pressure greater than 55%. One patient, with a subarachnoid hemorrhage, received an injection of 7.3 mg/kg, considerably higher than the usual dose (4.74 ±.83 mg/kg) in our experience. Two patients had been given concurrent doses of potential vasodilators—one receiving aminophylline and the other, hydralazine hydrochloride. A fourth patient with a history of chronic hypertension refractory to routine antihypertensive therapy received an oral dose of methyldopa, a parenteral dose of phenobarbital, and an infiltrate dose of diazoxide within one hour prior to an effective diazoxide