Context: As thyroid cancer incidence rises, more patients undergo thyroid surgery. Although postoperative complication rates have been reported in single institution studies, population-based data are limited. Objective: To determine thyroid cancer surgery complication rates and identify at-risk populations. Design/Setting/Patients: Using the Surveillance, Epidemiology, and End Results-Medicare database, we evaluated general complications within 30 days and thyroid surgery-specific complications within 1 year in 27,912 patients who underwent surgery for differentiated or medullary thyroid cancer between 1998 and 2011. Multivariable analyses of patient characteristics associated with postoperative complications were performed. Main Outcome Measures: General and thyroid surgery-specific complications. Results: Overall, 1820 (6.5%) patients developed general postoperative complications (fever, infection, hematoma, cardiopulmonary, and thromboembolic events) and 3427 (12.3%) patients developed thyroid surgery-specific complications (hypoparathyroidism/hypocalcemia and vocal cord/fold paralysis). In multivariable analyses, general and thyroid surgery-specific complication rates were significantly higher in patients >65 years (odds ratio [OR] 2.61, confidence interval [95% CI] 2.31, 2.95; OR 3.12, 95% CI 2.85, 3.42), those with a Charlson/Deyo comorbidity score of 1 (OR 2.40, 95% CI 1.66, 3.49; OR 1.88, 95% CI 1.53, 2.31) and ≥2 (OR 7.05, 95% CI 5.33, 9.56; OR 3.62, 95% CI 3.11, 4.25), and those with regional (OR 1.18, 95% CI 1.03, 1.35; OR 1.31, 95% CI 1.19, 1.45) or distant disease (OR 2.83, 95% CI 2.30, 3.47; OR 1.85, 95% CI 1.54, 2.21), respectively. Conclusions: The rates of thyroid cancer surgery complications are higher than predicted, and patients with older age, more comorbidities, and advanced disease are at greatest risk. This has implications for patients undergoing thyroid cancer surgery. Efforts to reduce complications are needed. Acknowledgments: M.P. is funded by the National Institute on Aging of the National Institutes of Health under Award K08 AG049684 and a Career Development Pilot Grant from the Cancer Control and Population Sciences Program at the University of Michigan. M.R.H. is funded by Grant R01 CA201198 from the National Cancer Institute and Grant R01HS024512 from the Agency for Healthcare Research and Quality. The Punya Foundation for Thyroid Cancer Research also provided support for this project. The content is solely the responsibility of the authors and does not necessarily represent official views of the National Institutes of Health or Agency for Healthcare Research and Quality. No competing financial interests exist. Runtime of video: 5 mins 23 secs Abstract reproduced from Papaleontiou M, Hughes DT, Cui G, Banerjee M, Haymart MR. Population-Based Assessment of Complications Following Surgery for Thyroid Cancer, Journal of Clinical Endocrinology and Metabolism, 2017, 102(7); 2543–2551, by permission of Oxford University Press and the Endocrine Society.