DURING THE COURSE of renal insufficiency, edema frequently develops. The management of this edema offers a therapeutic challenge of somewhat greater magnitude than that met in cardiac decompensation and hepatic cirrhosis. The edema of uncomplicated cardiac failure usually responds well to the saluretic agents currently available including the organic mercurials, the carbonic anhydrase inhibitors, the benzothiadiazines, and the aldosterone antagonists. The response in hepatic cirrhosis is not quite so predictable, but is usually good. The response in renal insufficiency, however, is almost predictably poor.1 Recently, furosemide, a newly synthesized monosulfamoylanthranilic acid derivative, has been shown to be a potent diuretic agent, superior to the thiazides.2-5 We have studied the diuretic action of furosemide in a wide category of disease entities where the edema was usually resistant to prior diuretic therapy. This report concerns 22 courses of furosemide therapy in 14 patients who had renal insufficiency and in whom