The pheochromocytoma syndrome, caused by an abnormal secretion of catecholamines, is a rare pathology responsible for 0.1-2% cases of hypertension in the overall population considered. Although in the past we deemed the pheochromocytoma could cause prevalently the typical syndrome characterized by paroxysmal hypertensive crises, now we think that the usual clinical presentation is a continue or subcontinue hypertensive state (65%). In this paper the authors refer the clinical experience acquired in 25 years in the General and Cardiovascular Institute of the University of Milan (head: Prof. Ugo Ruberti), analyzing epidemiological aspects and pathogenesis of pheochromocytoma, with particular care to diagnostic methodologies and referring the therapeutic choices. From 1965 until today 40 patients have been surgically treated for pheochromocytoma mono or bilateral. 43 operations have been done, carrying out 46 adrenalectomy. Two complication must be referred: an ictus cerebri consequent upon an hypertensive crisis and one death caused by intraoperative ventricular fibrillation. Normalization of arterial pressure has been obtained in all patients.