Nine cases of medullary carcinoma of the thyroid gland (MTC) are reported. Four of the carcinomas were of the familial type. Five of the patients were men and four were women. Patient age ranged from 23 to 66 years, with a mean age of 40 years. The median age of the four patients with the familial MTC was 32 years. A total or a subtotal thyroidectomy was performed in four and five patients, respectively, associated with a modified neck dissection in six patients with involved cervical lymph nodules. An underlying pheochromocytoma of the left adrenal was excised in one patient prior to thyroidectomy. In all cases the parathyroid glands were identified, and in two cases of familial MTC, in which they were grossly enlarged, the parathyroid glands were removed. Four patients died as a result of their disease within 3 years, whereas patients are well 4 to 12 years after surgery. The best chance of cure lies in early diagnosis and an aggressive surgical removal of the primary tumor and any cervical metastases.