In the present study, relative expression levels of COX-1 and COX-2 gene in the fine needle aspiration biopsy (FNAB) washouts and in postoperative tissue of patients with papillary thyroid carcinoma (PTC), Hashimoto thyroiditis (HT) and nontoxic nodular goitre (NNG) were evaluated. This evidence concerns the gene PTGS1 and differentiated thyroid carcinoma.