Background: Anaplastic thyroid carcinoma is an extremely aggressive cancer that has a very poor outcome. We have analyzed predictive factors for overall survival and different therapeutic modalities that could help to determine the optimal therapy for this carcinoma.Methods: We performed a retrospective analysis of data from 54 cases of anaplastic thyroid carcinoma to evaluate demographic, pathological, and clinical characteristics, along with therapeutic modalities that affected survival. The Kaplan-Meier curve was used to visualize the cumulative probability of survival and comparison among/between groups was performed with the log-rank test. A multivariate Cox proportional hazards model was used to examine overall survival.Results: We observed overall survival percentages of 50% (one-year), 25% (2- year), and 5.6% (5-year). The 2-year overall survival was 41.7% for stage IVA, 31.5% for stage IVB, and 7.4% for stage IVC (P= 0.04). The 2-year overall survival rates were 59.3% for patients with negative margins, 30.1% for those with positive margins, and 0.0% in the group without thyroidectomy (P=0.005). Surgery plus postoperative radiotherapy indicated better 2-year overall survival (56%) compared to surgery alone (34.7%, Pone month, no reported metastasis at presentation, negative surgical margins, surgery, radiotherapy, and/or chemotherapy.Conclusion: Anaplastic thyroid carcinoma is an aggressive cancer with a very poor prognosis. Multimodality treatment may improve overall survival in these patients. Duration of symptoms, primary tumor size, distant metastases, surgical treatment, surgical margin status, radiotherapy, and chemotherapy are independent factors that affect prognosis.