Objectives: The aim of this study is to examine the effects of ultrasonography and serum anti-thyroid antibody (ATAb)levels in predicting malignancy in cases where molecular tests cannot be performed in indeterminate thyroid nodules. Methods: Ultrasonographic features of the dominant thyroid nodule of a total of 228 patients who were operated for nodular goiter were analyzed and preoperative serum ATAb levels were examined. Especially in Bethesda category 3 nodules correlation of these parameters with malignancy rates and Hashimoto’s thyroiditis (HT) was investigated. Results: Malignancy was detected in 24.5% (12/49) Bethesda Category 3 nodules. Anti-thyroglobulin (Anti-TG) and-or anti-thyroid peroxidase (anti-TPO) positivity in serum 36.5% (72/197) was correlated with histopathologically proven HT (p=0.001). Poor prognostic factors were found to be less common in HT-associated papillary thyroid cancer (PTC). Ultrasonographic characteristics such as hypoechogenicity, microcalcification, and border irregularity were significant in predicting malignancy in indeterminate nodules (p=0.038- 0.003- 0.004, respectively). The central vascularization pattern remained in the background compared to other parameters (p=0.059). In the presence of ultrasonographic halo, 92.7% (51/55) of the nodules were benign (p=0.001). Conclusion: In the management of thyroid nodules in indeterminate cytology, suspicious ultrasonographic features and Hashimoto's thyroiditis should be encouraging in making the surgical decision.