Anaplastic thyroid carcinoma is a rare, highly malignant tumor of elderly people. The purpose of this retrospective study was to characterize the patient population and to detect a potential subgroup with better prognosis or any intervention that would be useful. From 1967 through 1994 a total of 33 anaplastic thyroid carcinomas were operated on at the Second Department of Surgery, Helsinki University Central Hospital. There were 26 females and 7 males with mean age of 66.0 years (range 36–89 years). At the time of diagnosis 16 of 33 patients had distant metastases, and 32 of 33 of the tumors had invaded the thyroid capsule. Disease-specific survival was 9.7% (95% confidence interval from 2.0% to 25.9%) at 1 year using the product limit survival analysis. In the stepwise Cox proportional hazards regression model, local resectability (p= 0.0002), presence of distant metastases at diagnosis (p= 0.0014), radiotherapy (p= 0.014), and radioiodine ablation (p= 0.039) were independent prognostic factors. We concluded that even though statistically significant, independent, prognostic factors can be found the survival of the patients with the best prognostic characteristics is still poor. Only one patient, who had an anaplastic carcinoma focus within an encapsulated follicular thyroid carcinoma, survived in this series. At present there seems to be no surgical treatment that would be efficient for treating symptomatic anaplastic thyroid carcinoma.