Background: Nodular diseases of thyroid are characterized by the disordered growth of thyroid cells. Malignancies have been found in 9% - 15% of the nodules that were evaluated with FNA. US features can provide information about the malignant potential of thyroid nodules. FNA plays a crucial role in the evaluation of the thyroid nodule, with high diagnostic accuracy of 85%-94%. The objective of this study was to assess the utility of gray scale and color Doppler US findings in characterization of benign and malignant thyroid nodules in correlation with the pathological diagnosis. Methods: From November 2019 to April 2021, a total of 50 patients with solitary thyroid nodule underwent thyroid US. The US characteristics of each nodule were determined and was assessed using grey scale and colour Doppler. χ 2 tests were performed. Sensitivity, specificity, positive and negative predictive values were obtained. The results were then compared to the fine needle aspiration (FNA). Results: Statistically significant (P < .05) findings of malignancy were : taller than- wide shape (sensitivity, 73.1% ; specificity, 95.5% ),lobulated/poorly defined margins (sensitivity,69.2% ; specificity,95.5%), hypoechogenicity and marked hypoechogenicity, (sensitivity, 72.5% ; specificity, 95.5% ), thick incomplete /absent halo(sensitivity,88.5% ; specificity, 78.1%), central/ central > peripheral pattern of vascularity (sensitivity, 73.1% ; specificity,81.8% ) and associated cervical lymphadenopathy. Similarly statistically significant US findings for benign nodules were presence of wider than tall shape, well defined margins, hyperechogenicity, and presence of thin halo. Using a 5 category US classification system, the specificity and positive predictive value were high for malignant, possibly malignant, probably benign and benign US categories in the range of 93.18% to 100% and 78.57% to 100% respectively. Using multiple logistic regression, the overall diagnostic accuracy of thyroid US for differentiating a malignant lesion from a benign one in the present study was found to be 84.3 %. Interpretation And Conclusion: Taller-than-wide shape, Lobulated/poorly defined margins, Hypoechogenicity and Marked hypoechogenicity, Microcalcifications and Central/ central > peripheral pattern of vascularity are helpful criteria for the discrimination of malignant from benign nodules. Thyroid US achieved a good overall diagnostic accuracy in the categorization of benign and malignant thyroid nodules.