In the years 1979-1988, operations were performed on 41 anaplastic carcinomas and 11 sarcomas of the thyroid gland. Out of these cases reoperation was indicated in 18 patients (34.6%): in 11 cases only a palliative tracheotomy could be done (group I), whilst in the remaining 7 patients surgical removal of the recurrent tumour was possible (group II). Analysis of group II patients revealed that the initial surgical intervention had been a macroscopically radical operation. The difference between the survival rates of both groups was highly significant (group I 64 days, group II 412 days mean survival). Despite the fatal prognosis of these highly malignant tumours, we conclude that reoperation for the removal of a recurrent tumour is advisable in those patients in whom the initial operation was a radical excision. Longer survival rates and improved quality of life were achieved. If the initial operation was merely palliative, then only a tracheotomy is the likely procedure in case of recurrence.