The etiology of persistent hypokalemia and renal potassium loss was investigated in three children. Each had normal blood pressure but low plasma aldosterone values in relation to elevated plasma renin activity. None had a history of licorice abuse, laxative or diuretic use, persistent vomiting or diarrhea, pyelonephritis, or diabetes insipidus. Additional studies in one patient showed low prostaglandin E excretion and a normal platelet aggregation response to epinephrine and ADP. Although certain aspects of this condition resemble Bartter syndrome, the low concentrations of aldosterone and the absence of evidence for mineralocorticoid excess suggest a previously undescribed syndrome.