AbstractIntroduction: Thyroid Fine Needle Aspiration (FNA) has been widely used as a firstline investigation to assess thyroid nodules, as it is rapid, cost effective, safe and reliable.To bring uniformity and standardization in thyroid cytology reporting, “The Bethesda System for Reporting Thyroid Cytopathology” (TBSRTC) was introduced and it is gaining acceptance. This study has been undertaken to evaluate the reproducibility using TBSRTC system while reporting thyroid FNACs and to find out the utility of Bethesda system after correlating with the histopathology. Methods: A retrospective study was conducted in which 506 cases of thyroid aspirates were reclassified according to TBSRTC in to six categories by two cytologists separately and reproducibility of the system was assessed. In 97 cases histopathological correlation was available and risk of malignancy in all these TBSRTC categories was calculated. Results: ategory wise distribution of aspirates was non diagnostic (ND) 1.38%, Benign(BN) 88.15%, Follicular neoplasm (FN) 2.38%, follicular lesion of uncertain significance(FLUS) 2.96 %, suspicious of malignancy(SM) 1.38% and malignant category (3.75%). Overall Percentage of agreement between the two cytologists was 97.5% and rate of disagreement was more in follicular lesion of undetermined significance, follicular neoplasm and suspicious category. On cytohistological correlation, malignancy rate in different categories are ND 0%, BN 1.4%, FLUS 20%, FN 28.6%, SM 60% and MGT 100%. Conclusions: It was observed that standardized nomenclature of the Bethesda system has brought much needed clarity in thyroid FNAC reporting. Substantial interobserver agreement was found for thyroid cytological lesions using Bethesda reporting. Along with MGT category, the FLUS, FN and SM categories carry higher malignancy risk.