The association of medullary thyroid cancer and pheochromocytoma with mutiple mucosal neuroma is termed MEN2B. We report a case of a 37-years-old man with MEN2B accompanied with delayed-onset bilateral pheochromocytoma. He had been diagnosed MEN2B ten years preriously. At that time, he had medullary thyroid cancer, mucosal neuroma on the tongue and lips, congenital megacolon and Marfanoid features. He underwent total thyroidectomy and cervical lymph node resection. After 12 years, he was found to have multiple cervical lymphadenopathy, and admitted for chemotherapy. However the chemotherapy was interrupted because of severe abdominal distention and headache accompanied with hypertension. The Abdominal CT scanning and hormonal study revealed bilateral adrenal mass and elevated 24-hour urine levels of VMA and metanephrine. Additional neck node lymph dissection and laparoscopic adrenalectomy are planned. As this disease can be lethal, early diagnosis based on prompt recognition of the characteristic phenotypic features followed by surgical treatment should improve the outcome. Family screening is essential to identify at-risk family members for prophylactic treatment. The possibility of delayed pheochromocytoma in MEN2B such as found in this case advocates regular blood pressure monitoring and close observation in those MEN2B patients without pheochromocytoma.