Medullary thyroid carcinoma is the third most common thyroid carcinoma after papillary and follicular carcinoma. It accounts for approximately 2% of all cases of thyroid cancer and arises from parafollicular C cells that secrete calcitonin. Sporadic medullary thyroid cancer is the most common type (75%), and it is followed by hereditary carcinomas (25%) that are autosomally dominantly inherited. Hereditary cancers are more often bilateral and more aggressive. They are more often associated with a larger number of other tumors. They are result of mutations in RET protooncogene within MEN2A and MEN2B syndrome. Clinically, cancer is most often presented as a thyroid nodule that is accidentally detected on physical examination. The diagnosis of medullary thyroid carcinoma is made on the basis of ultrasound, FNA and measurements of serum calcitonin and CEA. Normal calcitonin levels are less than 10 pg/ml. DNA analysis is often used to confirm mutations in RET protooncogenes, and if the presence of a mutation is proven, it is important to screen patients’ relatives. Total thyroidectomy is the only therapeutic method that has promising results, and it is often combined with neck dissection. Unfortunately, at the time of diagnosis, most cancers are already at an advanced stage. In such cases, systemic therapy with vandetanib and cabozantinib may be considered. Chemotherapy and radiotherapy do not have satisfactory success in the treatment of medullary cancers, but they are useful in preventing local complications.