Gordon's syndrome was diagnosed in a 19-year-old woman who had hypertension, hyperkalemia and hyperchloremic acidosis. In family screening, hyperkalemia and hyperchloremic acidosis were also found in the patient's mother and brother. The proband and her brother were studied and showed normal glomerular function with normal renal sodium conservation and urine acidification mechanisms. The levels of plasma aldosterone were normal in both subjects. The renin activity was low in the proband but normal in the brother. Both the basal and the volume-stimulated plasma concentration of atrial natriuretic peptide was low in the two patients. As compared with controls, the kaliuretic response to infusion of sodium chloride was not decreased in the patients. Hydrochlorothiazide promptly corrected the acidosis and the hyperkalemia as well as normalized the raised blood pressure of the proband. We suggest that a deficiency of atrial natriuretic peptide rather than an unusual avidity for sodium chloride reabsorption by the renal tubules plays a significant pathogenetic role in Gordon's syndrome.