Piretanide is a high-ceiling, loop-active diuretic that has been developed for treatment of congestive heart failure, hypertension and edematous states caused by renal and hepatic diseases. Piretanide is structurally related to furosemide and bumetanide; when administered orally, 6 mg of piretanide is as effective as 40 mg of furosemide, and when administered intravenously, 12 mg of piretanide is as effective as 40 mg of furosemide. Piretanide enhances water and sodium excretion in patients with congestive heart failure, with nephrotic syndrome and with cirrhosis and ascites. Adverse effects reported to date are limited to those attributable to excess loss of fluid and electrolytes. Under some conditions, piretanide appears to be less potassium wasting than thiazide diuretics or other loop-active diuretics.