Medullary thyroid cancer is a neuroendocrine tumour originating from the parafollicular C cells of the thyroid gland that accounts for about 5-10% of all thyroid carcinomas. It may occur either sporadically (75%) or in familial forms (25%) in familial medullary thyroid carcinoma and multiple endocrine neoplasia types 2A and 2B. Distinct clinical phenotypes in hereditary medullary thyroid cancer result from different missense germline mutations in the RET protooncogene. Medullary thyroid cancer produce calcitonin, measurement of which indicates the presence of tumour in at-risk individuals and the effectiveness of management in treated patients. Prognosis of patients with medullary thyroid cancer is variable, but the more constant factors that affect it are the stage of disease and the age of the patient. The goal of treatment of patients suffering from medullary thyroid cancer is to detect and surgically remove disease at its early stage. Total thyroidectomy with local nodal dissection leads to achievement of biochemical cure in more than 80% of cases. The tumour does not take up radioactive iodine, is relatively radioresistant, and there is no known effective systemic therapy for this cancer. The purpose of this article is to summarise the present state of knowledge on the etiology, clinical presentation, management, prognosis, and genetics of medullary thyroid cancer. (Pol J Endocrinol 2008; 59 (5): 446-455)