Over a two-year period, seven hundred twenty-three operations for thyroid disease were performed in the department of endocrine surgery on 717 patients; 7.1% of these patients had neoplastic lesions. If we consider only the solitary nodules, the incidence is 8.8%; while it is only 5.0% in patients with diffuse goiter. In 27.5% of the cases of thyroid neoplasm, peroperative analysis on thyroid tissue is falsely encouraging; yet, on the whole, such analysis reassures 98% patients. Preoperative fine needle aspiration and cytology--of little impact in that series--can bring interesting informations in particular circumstances, while keeping in mind that microscopic diagnosis of follicular carcinoma of the thyroid is histological and not cytological.