© 2019 Wiley Periodicals, Inc.Background: In this study, we aimed to evaluate ultrasonographical and cytological features of thyroid nodules in patients who were treated with radioactive iodine (RAI) for hyperthyroidism years ago. Methods: Patients who had a history of RAI treatment for hyperthyroidism and had thyroid nodules that were evaluated with fine-needle aspiration biopsy (FNAB) were included in the study. Results: There were 27 patients (22 female and 5 male) with a mean age of 59.3 ± 13.5. The indication for RAI treatment was Graves in 5 (18.6%), toxic nodular or multinodular goiter in 16 (69.2%), and unknown in 6 (22.2%) patients. A total of 48 thyroid nodules were evaluated with FNAB and cytological diagnosis were benign in 24 (50.0%), nondiagnostic in 15 (31.2%), atypia of undetermined significance in 5 (10.4%), suspicous for malignancy in 2 (4.2%), and malignant in 2 (4.2%) nodules. Thyroidectomy was performed in 10 patients, 5 were benign (50.0%), and 5 (50.0%) were malignant histopathologically. Ultrasonography features of 31 cytologically/histopathologically benign and five cytologically/histopathologically malignant nodules were compared. Prevalence of isoechoic nodules was higher in benign nodules (P =.025). Macrocalcification was observed in 4 (80.0%) of malignant and 10 (32.3%) of benign nodules (P =.042). Conclusion: In patients with a history of RAI treatment for hyperthyroidism, thyroid nodules with suspicious ultrasonography features, particulary hypoechoic appearence and macrocalcification, should be evaluated with FNAB irrespective of the time elapsed after RAI treatment.