Oncocytic carcinoma (Hürthle cell carcinoma—HCC) of the thyroid gland is an unusual and relatively rare tumor accounting for approximately 3–10% of all differentiated thyroid cancers. There is no accepted paradigm for the pathogenesis of oncocytic/HCC and there is no universally accepted standardized treatment of such tumors. Oncocytic/HCCs have characteristic histological features and also have a low tendency to take up radioactive iodine (RAI) on imaging. The likelihood of nodal metastases is greater in oncocytic/HCC than in follicular thyroid carcinoma; but is not as great as with papillary thyroid carcinoma. This chapter discusses the controversies associated with oncocytic/HCCs, including epidemiology, pathophysiology, etiology (risk factors), clinical presentation, differential diagnosis, and investigations (workup) including laboratory studies, imaging techniques, and cyto-histopathological and electron microscopical examinations. It also explores the staging and treatment options available for these tumors, which include surgical treatment (lobectomy, total thyroidectomy) and adjuvant therapy (medical, radioactive iodine, external beam radiation therapy, direct targeted therapy, systemic chemotherapy). Finally, this chapter discusses the appropriate follow-up of patients with oncocytic/HCC, the potential complications (surgical and nonsurgical), as well as the necessity of patient education. Radiation precautions should be explained clearly and in detail to patients who will be receiving RAI treatment. Women of childbearing age should be advised not to become pregnant for at least 1 year after treatment with RAI.