We present a case of MEN 2B diagnosed in a 23 year-old patient on the basis of bilateral pheochromocytoma and medullary thyroid carcinoma. This young male patient also had multiple paragangliomas located along the spine, marfanoid features of body habitus and numerous mucosal neuromas of the oral cavity and intestinal ganglioneuromatosis. The patient was hospitalised several times between the ages of 11 and 14 due to heart rhythm disorders (tachycardia, multiple supraventricular beats) and pain in the precardiac area. Elevated blood pressure was not observed at that time. In 2010, the patient was admitted to hospital due to abdominal pain, nausea, vomiting and hypertension; bilateral adrenal tumours were then detected. The patient was referred to the Department of Endocrinology in Szczecin, with suspected pheochromocytoma in order to continue the diagnostic process. This resulted in the diagnosis of bilateral pheochromocytoma and medullary thyroid carcinoma. On the basis of the whole clinical picture, the diagnosis of MEN 2B was established and subsequently confirmed with genetic test results. Following the removal of adrenal tumours and thyroidectomy, the patient was referred to the Cancer Centre and Institute of Oncology in Gliwice for further treatment (X-ray therapy and further surgery due to recurrence of medullary carcinoma). This article presents a case of late MEN 2B diagnosis despite the presence of clinical symptoms suggestive of Multiple Endocrine Neoplasia observed from early childhood.