BACKGROUND In elderly patients, spinal anesthesia-induced hypotension (SAH) can be frequently caused by reduced preload and stiff ventricles. The primary purpose of this study was to investigate the ability of ultrasonographic carotid artery flow measurements during the passive leg raise (PLR) test to predict SAH in elderly patients. The correlation between preoperative transthoracic echocardiography (TTE) measurements and SAH was also investigated. MATERIAL AND METHODS The patients aged over 65 years scheduled for elective surgery under spinal anesthesia were recruited. Preoperative TTE was performed in all patients. Corrected carotid flow time and carotid blood flow were measured in the supine, semirecumbent, and PLR positions. Ultrasonographic carotid artery flow and preoperative TTE measurements were compared between patients who developed SAH and those who did not. Receiver operating characteristic (ROC) curve analysis and logistic regression analysis were used to test the association with SAH. RESULTS SAH occurred in 17 of 50 patients. Carotid blood flow in the semirecumbent position and preoperative mitral inflow E velocity could predict SAH, showing an area under the ROC curve of 0.754 (95% CI, 0.612-0.865) and 0.775 (95% CI, 0.634-0.881), respectively. However, according to the multivariate analysis, the independent risk factor for SAH was mitral inflow E velocity (OR 0.918, 95% CI 0.858-0.982, P=0.013). CONCLUSIONS In elderly patients, ultrasonographic carotid artery flow measurements failed to predict the occurrence of SAH. Only preoperative mitral inflow E velocity of TTE was selected as an independent risk factor for SAH.