Fine-needle aspiration cytology (FNAC) has become a widespread procedure for the study of thyroid nodules (TN). Some authors recommend the practice of repeated punctures for their follow-up. This study was done to determine the usefulness of repeated FNAC in patients with benign nodular thyroid disease. We have studied 251 fine-needle re-aspirations performed on 116 females aged 45.6 +/- 14 years with benign nodular thyroid disease. The time elapsed between each consecutive FNAC was 1 year. No patients presented any changes in the size or consistency of their nodular goiters during this period; all FNACs were carried out by the same physician in the same thyroid area according to the Löwhagen technique, with a minimum of two or three aspirations of each nodule, and processed in the same way and valued by the same cytologist without any knowledge of previous cytological diagnoses. These were done using strictly classical criteria (Löwhagen). One hundred and five out of 116 patients (90.51%) with two consecutive FNACs (210) showed identical cytological diagnoses in the two specimens studied. The remaining 11 patients (9.48%) with two FNACs were diagnosed with colloid goiter and cyst alternately. Fifteen out of 19 patients (78.94%) with three FNACs showed identical cytological diagnoses in the three samples and the rest (21%) also demonstrated alternate diagnoses of colloid goiter and cyst. Our results show that the routine performance of repeated FNAC in the follow-up of females with benign nodular thyroid disease, without any clinical changes, is of limited usefulness.