Three patients with hypertension and hypokalemia demonstrated the low level plasma renin activity and elevated aldosterone level. Plasma renin activity did not increase during volume depletion and aldosterone level did not suppress during salt loading. Computerized tomography of abdomen showed well-defined oval mass of low density in right adrenal gland in all 3 cases. Right adrenalectomy was done and pathologic finding showed adrenal adenoma. Postoperatively there were reversal of hypertension and hypokalemia. We present three cases of primary aldosteronism which were all located in right adrenal gland, with brief review of literatures (J Kor Soc Endocrinol 6:377~383, 1991)