Introduction:Thyroid swelling is a significant clinical problem in general population but majority of them are benign lesions. Fine Needle Aspiration Cytology (FNAC) is well established first line diagnostic test for evaluation of diffuse thyroid lesions. The main purpose of FNAC is to confirm benign lesions and thus reducing unnecessary surgery. Aims and Objectives:To study various lesions of thyroid swelling by FNAC and correlation between the cytological and histopathological diagnosis.Materials and Methods: A prospective study was conducted in Department of Pathology, Tertiary care center, Nashik from August 2020 to December 2022 to evaluate the diagnostic accuracy of FNAC in lesions of thyroid. The cyto-histological correlation was done in all the cases. Results:Out of total 113 cases, 3 cases (2.65%) were diagnosed as non-diagnostic (Bethesda category I), 87 cases (76.98%) as Benign (Bethesda category II), 9 cases (7.96%) as Atypia of undetermined significance,13 cases (11.50%) as Follicular neoplasm (Bethesda category IV) and 1 case (0.88%) as Suspicious of neoplasm (Bethesda category V) on cytological examination. On histopathological study,97 cases (85.84%) were diagnosed as nonneoplastic and benign while 16 cases (14.16%) as malignant. The PPV, NPV, Sensitivity, Specificity of FNAC were 92.85%, 94.25%, 72.22% and 98.79% respectively. The diagnostic accuracy was 94.05%. Conclusion: Simplicity, diagnostic accuracy and most of all cost effectiveness have given FNA the status of the first line diagnostic test in preoperative evaluation of thyroid lesions. FNA has been shown in to be the safest and most accurate of diagnostic tools in thyroid lesions.