Pheochromocytoma is a functioning tumor occurring in the chromaffin tissue and catecholamines from the tumor cell lead to the symptoms such as hypertension, palpitation and headache. Among the problems arising in the anesthetic management, the excessive secretion of catecholamines by the induction of anesthesia and the tumor mass manipulation causes a hypertensive crisis and the arrhythmia. Also, after the removal of the tumor mass, it must be remembered that a profound hyptension may follow due to abrupt lowering of catecholamine level. We experienced two cases of anesthetic management of pheochromcytoma using enflurane. In one case of sufficient preoperative management, it was performed uneventfully without symptoms such as hypertensive crisis and arrhythmia during the anesthetic management. But, in the other case with insufficient preoperative management, the patient was unstable due to hypertnesive crisis, premature contractions of the ventricle and tachyarrhythmia during the anesthetic management.