The aim of our study was to evaluate the presence of incidental differentiated thyroid carcinomas, at final histological examination, in patients undergoing thyroidectomy or lobectomy for presumed benign pathology or in those with cytological diagnosis of indeterminate nodules (TIR3).457 patients who underwent surgery for benign disease and 179 patients with indeterminate FNA were included in our study.77 out of 457 patients had the diagnosis of differentiated thyroid carcinoma. 29 out of 179 patients had the same diagnosis as previous ones, but not on the undetermined FNA nodule. In the most of the cases, the istotype was follicular variant of papillary carcinoma.The incidence of incidental carcinomas, approximately the same in the two groups of patients, respectively 16.8% and 16.2%, shows that there is still a group of patients with benign thyroid disease escaping a careful ultrasound evaluation and therefore a targeted FNA. Even in patients with indeterminate cytology, the presence of an incidental carcinoma suggests that on the one hand there has been an overestimation and on the other a non-recognition of the really suspect nodule. Although in most cases it is a microcarcinoma, we must not overlook the presence of many tumors at stage T3.Surely the analysis of the set of risk factors with a wider application of molecular biology surveys will in the future lead to better selection of patients to undergo surgery sooner than those that can be followed in follow up even for a longer period of time.Differentiated thyroid carcinoma, Fine needle aspiration, Incidental carcinoma.