Between June 1 1975 and Dec. 31 1989 at the surgical clinic for adults in Prague-Motol 44 patients were operated on account of medullary cancer of the thyroid gland (MCT). In the great majority total thyroidectomy (TTE) was performed which in this disease is an absolute indication. In some instances the operation was supplemented by lymphadenectomy. The prognosis of the familial type of the disease was more favourable due to the possibility of active screening of the tumour. The authors reached the conclusion that the therapeutic results in MCT can be improved by early diagnosis as well as sufficiently radical surgical operations.