Background: Relative hypovolemia may predispose to severe or prolonged hypotension after spinal anesthesia in patients undergoing orthopedic surgeries. Empirical administration of fluid preload is time consuming, costly and might lead to volume overload, especially in elderly patients. Therefore, predicting post spinal hypotension is of great importance to reserve fluid infusion for susceptible patients. Ultrasonographic evaluation of the internal jugular vein (IJV) diameter has been used to estimate intravascular volume in the ICU. Therefore, we investigated the efficacy of sonographic measurements of the internal jugular vein parameters for predicting post spinal hypotension in patients undergoing orthopedic surgeries. Methodology: The study was conducted on 62 patients scheduled for orthopedic surgeries. Sonographic measurements of IJV diameter and cross-sectional area were recorded at supine and Trendelenburg position before spinal anaesthesia. Blood pressure was monitored for 15 minutes for all patients and hypotension was documented. Results: Twenty-eight patients (45.2%) developed hypotension. The rate of increase in the diameter and cross-sectional area of the IJV with the change in patient’s posture was significantly higher in hypotensive patients. According to ROC curves analysis, a rate of increase of 12.36% in IJV diameter, and a rate of increase of 25.55% in IJV cross sectional area showed moderate specificity and sensitivity in the prediction of spinal hypotension. Conclusion: Preoperative sonographic measurements of the internal jugular vein diameter and crosssectional area at supine and Trendelenburg position can predict the occurrence of post-spinal hypotension.