Spironolactone, an aldosterone-antagonist, was administered to 4 adults and 2 children in the treatment of refractory edema of renal origin. The 6 case histories presented show that an excellent response, indicated by loss of edema, was obtained in 5. Three of the adults with azotemia developed hyperkalemia, so that the spironolactone had to be withdrawn. One of these patients showed electrocardiographic signs of hyperkalemia. When spironolactone is used in patients with azotemia observation of serum potassium levels is considered mandatory. The drug does not alter the underlying disease process, but the authors consider it a useful adjunct in the treatment of patients refractory edema of renal origin, especially in children with the nephrotic syndrome.