It is well known that pheochromocytoma is much more likely to occur in persons having multiple neurofibromatosis than in otherwise normal persons. In addition, a number of cases of the simultaneous occurrence of pheochromocytoma and von Hippel-Lindau's disease have been described in recent years. The authors report 2 cases of the latter association of lesions in a mother and son, both of whom had cerebellar hemangioblastoma and bilateral pheochromocytomas. Von Hippel-Lindau's disease and multiple neurofibromatosis are commonly considered to be related dysplasias of those tissues which arise from the neurectoderm. Since the adrenal medulla is also of neurectodermal origin, it is not surprising that these disorders are associated with a high incidence of pheochromocytoma.