INTRODUCTION Anaplastic thyroid cancer is a rare and fatal malignancy, associated with significant local tumour and often treatment related morbidity. We report our experience in treating this cancer over a 20-year period. METHODS A retrospective review of prospectively collected data from a single Australian Institution (Alfred Health Radiation Oncology) was carried out on patients referred with anaplastic thyroid carcinoma between 1992 and 2013. RESULTS Thirty patients (17 females and 13 males) were identified with a median age at presentation of 72 years. At presentation, six (20%), 14 (47%) and 10 (33%) patients had stage IVA, IVB and IVC disease respectively. Thirteen patients underwent radical surgical resection with five having microscopic residual (R1) and eight having macroscopic residual (R2) disease. Twenty-eight patients were offered radiotherapy with 27 proceeding with treatment. Of those who received radiotherapy, three, six and 18 were treated with adjuvant, definitive and palliative intent respectively. Six patients had concomitant chemotherapy of which three received trimodality therapy. Only one patient experienced a grade 3 toxicity (oesophagitis). Median survival was 5.3 months and at last follow-up or time of death, 19 of 27 (70.4%) maintained loco-regional control. All patients who had R1 surgical resections and radiotherapy had loco-regional control. Seven of nine (77.8%) and 12 of 18 (66.7%) achieved loco-regional control after receiving definitive or palliative radiotherapy, respectively. CONCLUSIONS Our study suggests that radiotherapy with or without surgery or chemotherapy is well-tolerated and results in durable loco-regional control in a high proportion of patients with anaplastic thyroid carcinoma.