Furosemide was administered intravenously to 41 patients with edema who had become refractory to both thiazides and organomercurials. Repeated doses of 80 to 160 mg completely cleared peripheral edema in all patients and pulmonary congestion (roentgenographically demonstrated) in nine of 12 patients by the fifth day. Fifteen minutes after the injection, there was a 13-fold increase in urinary output and more than a fourfold increase in urinary sodium excretion. The urinary sodiumpotassium excretion ratio during furosemide-induced diuresis was increased more than onefold. Potassium excretion was not increased unless excessive diuresis occurred.