Historically, thyroid surgery has been fraught with complications. Injury to the recurrent laryngeal nerve, superior laryngeal nerve, or the parathyroid glands may result in profound life-long consequences for the patient. To minimize the morbidity of the operation, a surgeon must have an in-depth understanding of the anatomy of the thyroid and parathyroid glands and be able to apply this information to perform a safe and effective operation. This article will review the pertinent anatomy and embryology of the thyroid and parathyroid glands and the critical structures that lie in their proximity. This information should aid the surgeon in appropriate identification and preservation of the function of these structures and to avoid the pitfalls of the operation. Clin. Anat. 25:19–31, 2012. © 2011 Wiley-Liss, Inc.