Out of a total of 550 patients with thyroid cancer diagnosed over the 16-year period 1972-June 1989, 44 showed undifferentiated carcinoma and were treated by thyreoidectomy and early postoperative external irradiation. In order to analyse the outcome in patients treated by primary surgery in contrast to patients treated by means of a multimodal therapy concept we compared our surgical procedures with regard to primary surgical approach, early postoperative course, operative complications and survival to the data on the multimodal therapy concept of the Karolinska Hospital reported by E. Tallroth et al. 1987. A significantly better survival was correlated with radical (n = 20) versus palliative tumour resection (n = 24) (p less than 0.001), and total thyroidectomy (n = 25) versus subtotal thyroidectomy (n = 19) (p less than 0.006). Radical surgery with early postoperative external irradiation revealed no postoperative mortality and no symptomatic cervical tumour recurrence. By contrast, palliative surgery, particularly in the case of synchronous tracheotomy, was attended by a relatively high mortality (29%) and symptomatic local recurrences. The results of this study suggest that in undifferentiated thyroid carcinoma an attempt at radical tumour resection should be undertaken, since multimodal therapy procedures revealed a significantly highly complication rate (up to 36%) and, in comparison with a radical surgical treatment policy, showed a higher rate of local recurrences (0% vs. 48%) and a lower survival (mean survival 42 vs. 15 months).