The utility of fine needle aspiration (FNA) and physical examination for selecting patients with palpable thyroid nodules for surgery was evaluated in 795 consecutive cases. Surgery was performed in 216 patients based upon the cytological diagnosis and clinical criteria. Excluding 42 patients who were lost to follow-up, the remaining 537 were regularly followed up (range, 2-10 years). Cytological findings were classified as malignant, histologic control recommended (suspicious), follicular tumor, benign, and unsatisfactory. Thirty-six aspiration biopsies were positive for malignancy and the diagnosis was confirmed histologically in 34 of them. In 65 patients with final histological diagnosis of malignancy, cytology was positive in 34, suspicious in 20, benign in 3 cases, and unsatisfactory in 8. All patients with cytological diagnosis of follicular tumor had a benign lesion at histology. There were two false positive and three false negative cytological results among the 216 histologically confirmed cases. Excluding unsatisfactory specimen sensitivity, specificity and the predictive value for a positive and a negative result were respectively 95%, 97.5%, 94.5%, and 97%. We conclude that FNA is a very reliable diagnostic test in the evaluation of thyroid nodules and is the best guidance in addition to clinical criteria for selecting patients to be submitted to surgery.