Medullary thyroid carcinoma (MTC) is a rare malignancy of the thyroid C cells. It occurs in hereditary (25% of cases) and sporadic forms, and aggressiveness is related to the clinical presentation (hereditary vs. sporadic) and the type of RET mutation present. In hereditary cases, early diagnosis makes preventative surgery possible. In established cases, thorough surgical extirpation of the primary tumor and nodal metastases has been the mainstay of treatment. Radioactive iodine, external beam radiation therapy (EBRT), and conventional chemotherapy have not been effective. Newer systemic treatments, with agents that target abnormal RET proteins, hold promise and are being tested in clinical trials for patients with metastatic disease.