Thyroid nodules are a common finding in clinical practice. Although ultrasonography is an accepted method for evaluating these nodules, Fine Needle Aspiration (FNA) is the procedure of choice for assessing the risk of malignancy. This study aims to determine the association between sonographic features of thyroid nodules based on Thyroid Imaging Reporting and Data System classification and the cytology results. In this prospective cohort study, 147 patients from Tehran Medical Imaging Center who had thyroid nodules underwent ultrasonography-guided FNA, and their sonographic features were recorded. The pathologic findings were also obtained according to the Bethesda system. Finally, the association between sonographic features and cytological results was analyzed. Eighteen (12. 3%) nodules were malignant, and 129 nodules (87. 7%) were benign. The association of TIRADS categories with the risk of malignancy is as follows: TIRADS 1 (n=0, 0%), TIRADS 2 (n=10, 16. 9%), TIRADS 3 (n=6, 10. 5%), TIRADS 4 (n=2, 16. 7%), and TIRADS 5 (n=0, 0%). The bloody lamellae of thyroid nodules were significantly correlated with the risk of malignancy (P<0. 05). However, there was no statistically significant association between the risk of malignancy and gender (P=0. 47), calcification (P=0. 9), firmness (P=0. 19), halo sign (P=0. 95), location of nodules (P=0. 35), and nodules' echogenicity (P=0. 058). Although there are trusted classifications such as TIRADS for categorizing thyroid nodules, there is still uncertainty in utilizing them, especially in the management of nodules classified as TIRADS 2, in which various sonographic features are shared between benign and malignant nodules.