Medullary thyroid carcinoma (MTC) accounts for 5–10% of thyroid malignancies and occurs in either a sporadic or a familial form. The familial form is inherited in an autosomal dominant pattern, and expressed clinically as multiple endocrine neoplasia (MEN), types IIa and IIb, or as familial MTC alone. This neoplasm is derived from the parafollicular or C-cells, and has the ability to secrete a variety of polypeptide hormones including calcitonin, which serves as a tumor marker for the presence of MTC. The development of a calcitonin radioimmunoassay and the screening of patients at risk for the familial forms of MTC allows the diagnosis of the neoplasm in an occult stage when total thyroidectomy results in virtually 100% cure. We will present our experience with the diagnosis, treatment, and postoperative follow-up of our patients with this interesting neoplasm.