This article describes the findings of a retrospective analysis of data obtained on 78 patients with medullary thyroid carcinoma (MTC), recorded between 1969 and 1986, and then followed at the Thyroid Center of Padua (Italy). The ages of the patients ranged between 15 and 89 years, with a median age of 45. The female to male (F:M) ratio was 2.9:1. All patients except 2 had total thyroidectomy. In 70 cases the tumor was of sporadic type; there were 3 familial non-multiple endocrine neoplasia (MEN) MTC; 3 MEN IIa; and 2 MEN IIb. The median duration of follow-up was 15.9 years (13 patients were followed up between 15 and 20 years, and 9 longer than 20). At diagnosis, the tumor was intrathyroid (stage I and II) in 31 patients, with local lymphnodes involved (stage III) in 41 patients, and with distant metastases (stage IV) in 6 patients. A total of 34 patients died (4 were at stage II at diagnosis, 26 at stage III, and 4 at stage IV); 4 of them died of unrelated causes, the others with tumor. The median survival rate of the deceased patients was 6 years (41% of these patients died within 3 years and 24% after more than 10 years); 76% of the deceased patients were older than 45 years at diagnosis. A total of 44 patients are still alive, 22 are alive free of disease (with follow-up between 10 and 24 years, median 14.2 years) and 22 are alive with disease (median follow-up 12.2 years). Only 30% of the patients of both these groups was older than 45 years at diagnosis. Survival is strongly related to tumor stage and to age at diagnosis, because only 8 of the 34 deceased patients were younger than 45 years (and 2 of them died of unrelated causes); moreover, patients who were treated at earlier stages of the disease had better prognosis. Survival rate at 10 and 20 years was 95% for patients with tumor limited to the thyroid, whereas it was 55% and 28.6%, respectively, for patients at stage III and IV. Bone metastases were correlated with worse prognosis than distant metastases only to soft tissues. The sex did not affect survival. None of the patients who had postoperative low serum calcitonin (CT) levels and no response to pentagastrin stimulation showed recurrences in the follow-up. In patients with postoperative elevated serum CT levels, recurrences of the tumor increased over time. However, 30% of these patients continued to show only elevated CT levels without evidence of the disease, even after 15 years.