Since the adrenal or parathyroid cancer is a clinically rare entity. We often have difficulty in its diagnosis and treatment. The adrenocortical cancer is usually classified into two categories--endocrinologically functioning or non-functioning. The incidence is not different between them. It is often found in an advanced stage as it does not show clinical manifestation before it has grown up to a large tumor. Only an effective agent for the adrenal cancer is op'-DDD so far. Recently, cisplatin, VP-16 (etoposide) and others are administered as trial use. Most of malignant pheochromocytomas are endocrinologically active and they often cause hypertension leading to death. Therefore it is important to control hypertension in malignant pheochromocytoma. Chemotherapy and irradiation are not effective for it. Recently, 131I-MIBG (metaiodobenzylguanidine) is found to be useful not only for diagnosis but also treatment of malignant pheochromocytoma. 131I-MIBG is accumulated specifically in the chromaffin cells and with helpful to find out metastatic foci. It is also used in a large amount as a specific irradiation therapy for this malignancy. Parathyroid cancer is found in approximately 3 percent of primary hyperparathyroidism. Clinically it usually reveal serum calcium level higher than 14 mg/dl, bone lesions and renal dysfunction in addition to palpable cervical tumors adhering with skin. Sometimes it is difficult to differentiate malignancy from adenoma in histology. Most cases develop local recurrences and distant metastases in due course and dies of hypercalcemia. It is very important to control hypercalcemia in inoperable cases. As both chemotherapy and radiation therapy render no effect on this malignancy. Surgery is a sole strategy for it.