Background: Fine-needle aspiration cytology (FNAC) in the diagnosis of thyroid nodules is an easy and cost-effective method. The increase in malignancy rates of the excised nodules due to the high sensitivity and specificity rates of the FNAC is remarkable. Aim: The aim of this study was to assess the effectiveness of FNAC in the evaluation of thyroid nodules by comparing the results with histopathologic evaluation and comparing the consistency of the results with the literature. Materials and Methods: In this study, 1607 FNACs of 1333 patients which were classified according to the Bethesda system and 126 histopathological evaluations obtained from this group were evaluated. The mean age of the patients was 51.24 (range: 17-89, 17% male and 83% female). The sensitivity, specificity, positive and negative predictive values, and accuracy rates were evaluated. Results: The sensitivity was 87.1% and specificity was 64.6%. The positive and negative predictive value and accuracy rates were 76.1%, 79.5%, and 77.3%, respectively. Conclusions: In our study, the evaluation of thyroid FNAC samples with Bethesda system highly correlated with the results of histopathological diagnosis. However, combination of additional and advanced diagnostic methods such as immunocytochemical studies and molecular pathology techniques enhance the prognostic value of FNAC in patients with atypia of undetermined significance or follicular lesion of undetermined significance, lesions suspicious for malignancy, and suspected follicular neoplasm.