The aim of this study was to evaluate the role of Fine Needle Aspiration Biopsy (FNAB) in the preoperative diagnostic management of patients with solitary or dominant thyroid nodules. This study was performed on 1054 patients followed for various thyroid disorders during a three year period (1992-1995). One hundred thirty eight patients were surgically treated, 61 after cytological indication and 77 after clinical indication, of these, 67 were cytologically negative and 10 were not conclusive. The cytological diagnosis was compared to the final histological result. Among the 138 cases, 27 were malignant, 39 were adenomas and 72 were benign lesions. Of the 67 cytologically negative cases, 63 (94%) were histologically benign, three were papillary carcinomas and one was an oxyphilic adenoma. Of the 45 cytologically suspicious aspirates, four were malignant neoplasias, 38 were follicular adenomas, two were hyperplastic goiters and one was an Hashimoto thyroiditis. All the 16 cytologically positive cases, were confirmed histologically. The limits of FNAB, which emerge from our and other studies, were based mainly in the difficulty of discriminating follicular adenomas from well differentiated follicular carcinomas. Nevertheless, FNAB with ultrasonographic support, has been unanimously accepted as a guide test in the selection of patients with thyroidal pathology who need surgery.