The incidence of primary aldosteronism is low, less than 1 to 2 percent of the hypertensive population. Since November 1984 till May 1996, 16 patients in Cathay General Hospital were diagnosed as Conn’s syndrome. Age ranged from 25 to 80. Five were males and 11 females. All patients presented with hypertension: systolic were from 140 to 194 mmHg and diastolic were from 74 to 120 mmHg; the mean blood pressure was 164/96 mmHg. Blood otassium evels were below 3 mEq/L in 11 of 16 cases. Plasma aldosterone levels ranged from 177 to 1408 ng/dl with mean of 659.8 ng/dl. Tumors were demonstrated by CT scan, 9 in right and 7 in left sides. Fifteen of 16 cases had surgical operations to remove the tumor masses.