A 22-year-old woman complained of paroxysmal face flushing, palpitation and hypertension. CT scan revealed 55 mm mass in the right adrenal gland. Hormonal examination showed highly elevated urinary catecholamines and their metabolites excretion. Histological examination of the removed right adrenal gland confirmed the diagnosis of pheochromocytoma. 4 years later we observed the recurrence of similar symptoms. After the hormonal examination and CT imaging left adrenalectomy was performed, because of the presence of 33 mm diameter tumor in the left adrenal gland. Young age of our patient and occurence of bilateral pheochromocytomas suggested multiple endocrine neoplasia type 2. DNA sequence analysis of peripheral white blood cells revealed that codon 609 in exon 10 of the RET gene was mutated from TGC to CGC. During the further follow up of this patient we found 5 mm mass in the left lobe of the thyroid. Result of cytological examination of this focal mass and elevated calcitonin level in the pentagastrin test suggested the diagnosis of medullary thyroid cancer which was later confirmed after total thyeoidectomy based on results of histopathology of tumor. No metastatic changes was found. DNA analysis of the somatic mutation of the RET protooncogene was useful for the early detection of medullary thyroid cancer in the case of the 30-year-old patient with MEN 2A.