Although magnesium sulfate is the most widely employed drug for the prevention and management of convulsions in eclampsia, studies have suggested that phenytoin may be more specific. To assess this issue, the author studied 22 patients with eclampsia who had received only a single dose of 1–2 mg of clonazepam following a first convulsion. In the hospital, patients were randomly assigned to receive a loading dose of 4 g of MgSO4followed by an infusion of 1–2 g/h, or a loading dose of 500 mg of phenytoin, followed by two 500 mg doses given over 4 hours at an interval of 12 hours. Periodic serum levels of Mg and phenytoin were determined 30 minutes after the loading dose and then every 6 hours. Blood pressures in excess of 115 mmHg diastolic were controlled with dihydralazine infusion. Side effects for each drug were recorded and pregnancy was terminated as soon as convulsions and hypertension were controlled.