Two rare cases of pheochromocytoma were reported. Case 1 was 39-year-old housewife who was referred for history of high fever with left hypochondralgia twice in the previous 15 months before coming to our department. The patient had neither elevation of blood pressure nor that of central and peripheral venous catecholamine concentration. A left suprarenal mass was found in CT, which was suggested to be a cyst due to the numerical value between 23-24. Further ultrasonographic study indicated a solid tumor. Left adrenalectomy was done. Histologically, some of the viable atypical adrenal cells were found in the capsulating tissue contained the necrotic material which was almost occupying the entire mass. Case 2 was a 64-year-old female with hypertension who was admitted for further examination. On the hospital course, the blood pressure returned to normal without medication. Circulating blood volume was extremely reduced (below 1/2 of normal), the replacement of which raised the blood pressure to cause hypertension. An angiographic study indicated only a right adrenal mass, whereas left adrenal venous catecholamine concentration was significantly higher than that of the right side. After confirming right adrenal with no other disorders by CT scan, right adrenalectomy was carried out. Intraoperative correction of hypertension has been sustained and cardiovascular symptoms have disappeared.