Oncocytic (Hürthle) cells are large thyroglobulin-producing epithelial cells that are present in both nonneoplastic and neoplastic thyroid lesions, which encompass pathological entities ranging from hyperplastic nodules with oncocytic/Hürthle cell metaplasia to oncocytic/Hürthle cell carcinomas. Oncocytic/Hurthle cell lesion is defined as a hypercellular lesion with a predominance of oncocytic/Hurthle cells (more than 75%) and a paucity of colloid on cytological examination. This chapter discusses the controversies of oncocytic/Hurthle cell lesions and the dilemma facing the clinician of how to diagnose and manage these patients with Hurthle cell lesions; what findings are significant and warrant surgical evaluation/intervention? And which may be observed?