Background: Fine needle aspiration cytology (FNAC) is the commonly used test for diagnosis of thyroid nodules. FNAC is a cost–effective procedure that provides specific diagnosis rapidly with minimal complications. Based on the cytology findings, patients can be subjected to surgery only in cases of malignancy, thereby decreasing the rate of surgery and its consequent complications. The purpose of our study was to find the diagnostic accuracy of FNAC in thyroid lesions and to compare it with histopathology. Materials and Methods: A retrospective hospital–based study was conducted at Department of Pathology, Darbhanga Medical College & Hospital, Laheriasarai, Bihar. Data were collected from the records of FNAC and histopathology of thyroid lesions, done in last 2 years duration. Analysis was done by entering data in SPSS software, and Chi–square test was applied to find statistical significance. Results: FNAC was done on 234 patients in 2 years duration. The most common thyroid lesions were benign [221 (94.4%)], followed by malignant only [6 (2.6%)], indeterminate [3 (1.3%)], and inadequate [4 (1.7%)]. Out of 221 (94.4%) benign thyroid lesions, 33% were simple colloid goiter, 27.6% goiter with cystic changes, 16.28% nodular colloid goiter, 10.41% lymphocytic thyroiditis, 4.53% thyroglossal cyst, 4.07% colloid goiter with hemorrhage, 0.9% were follicular adenoma, and others formed 3.17%. Out of six (2.6%) malignant thyroid lesions, three were papillary carcinoma and the other three were follicular neoplasm. Conclusions: The cytological criterion for the diagnosis of thyroid lesions as benign and malignant by FNAC is a highly reliable method for the diagnosis. FNAC showed sensitivity, specificity, and diagnostic accuracy of 100% in the diagnosis of malignant lesions like papillary carcinoma as well as thyroglossal cyst and abscess.