Background : Fine needle aspiration cytology(FNAC) is a simple, safe, rapid, minimally invasive, cost–effective diagnostic method for pre–operative investigation of thyroid nodules. The study was carried out to find the diagnostic accuracy of  FNAC in thyroid swellings and its correlation with histopathological diagnosis.

Materials and Methods : A retrospective study of 140 cases was done at MIMS, Mandya from January 2011 to December 2012. The cases for which both cytological and histopathological diagnosis were available was selected. Fine needle aspiration cytology results were compared with histopathological diagnosis following thyroid surgeries.

Results : Fine needle aspiration cytology diagnosis showed non–neoplastic lesions in 124(88.6%)cases and neoplastic lesions in 16(11.4%) cases. The commonest lesion in the thyroid gland was colloid goiter. Papillary carcinoma was the commnest malignant lesion. Out of 140 cases, histopathological diagnosis was available in 45 cases. Statistical data showed sensitivity, specificity and diagnostic accuracy as 90%,100 and 95.5% respectively to diagnose malignant lesions.

Conclusion : FNAC of the thyroid is simple, safe, cost–effective and accurate preoperative diagnostic test. Due to its high sensitivity, specificity and diagnostic accuracy early and accurate differentiation between benign and malignant thyroid nodules can be made which significantly reduces mortality as well as morbidity of patients.