Hurthle cell carcinoma according to the majority of authors is a distinct entity, histologically related to the well differentiated malignancies of the thyroid gland. Its biologic behaviour is more aggressive than other well-differentiated thyroid carcinomas, metastasizing to both regional nodes. Biologic behaviour does not correlate with histologic appearance. The authors report a personal series of 726 patients that underwent thyroid surgery. Hurthle cell tumours were found in 10.7% of benign adenomas and in 12% of all malignancies. Reliability of pre- and intraoperative diagnostic techniques and therapeutic options are discussed.