Primary aldosteronism (PA) is a relative new endocrine disease that account for almost 1-2% of the hypertensive population. In spite of the large number of reports there is still disagreement around the preoperative diagnosis and surgical treatment. In a nineteen year period from 1970 to 1989, 34 patients came to our Department with a diagnosis of Primary Aldosteronism. 18 patients were female. Mean age at time of diagnosis was 45.5 yrs. (range 27-67 yrs.). Mean follow-up was 71 months (range 1-227 months). Follow-up was achieved in all patient. Hypertension and hypokalemia were discovered in all patients. Three patients had extremely low values of potassium and presented severe metabolic, cardiac and neurologic troubles. Localization procedure techniques improved during this period of time and at this moment CAT scan appears to be the most accurate method. Flank incision was the approach of choice in all but four patients. No postoperative complications were recorded. Histology demonstrated an incidence of adenomas according to the literature. One patient had an adrenal carcinoma with functioning metastases. He was operated on several times in order to remove the functioning node metastases but finally died with widespread disease four years after the first surgical treatment. Another patient in this series died three years after the operation for an unrelated event. In 29 patients hypertension and hypokalemia disappeared while in two patient, one with an adrenal carcinoma hypertension increased. Primary aldosteronism is a rare endocrine disorder whose incidence is increased in the last years because of the improvement in diagnostic procedures.(ABSTRACT TRUNCATED AT 250 WORDS)