Five cases of pheochromocytoma are described in which sudden death was the form of the initial clinical presentation in almost all of them. After a brief review on the history and the incidence of the tumor within the general population, diverse cases are analyzed from a clinical point of view and in relation to the data appeared in the literature. In the analysis of the symptoms emphasis is placed on the important psychomotor manifestations which are present in the majority of those patients and which causes serious difficulties in the initial diagnosis. All of the patients showed signs of shock at the time of being observed or during the course of this observation, and in the majority of them the presence of acute pulmonary edema was confirmed; facts which we attribute to an initial hypertensive episode associated to a left heart failure. The onset of the crisis in two patients was related to known triggering factors: anesthesia and sulpiride. In other two patients associated conditions were diagnosed: medullary carcinoma of the thyroid gland in one of them, and cystic necrosis of the middle layer of the aorta in the other.