ABSTRACT Objective: The aim of this study was to compare the sensitivity and specificity of Pleth Variability Index (PVI) and distensibility of inferior vena cava (dIVC) in fluid responsiveness of patients with sepsis. Material and Methods: Forty patients over 18 years of age who underwent fluid replacement for sepsis in the intensive care unit were included in the study. In our study, the patients were divided into 2 groups as those who had less than 15% increase in cardiac output (CO), and those who had more than 15% increase in CO after fluid replacement (fluid responders and non-responders). Before fluid replacement, demographic data of the patients (age, weight, cause of sepsis, body surface area, SOFA score), vital parameters (systolic arterial pressure, diastolic arterial pressure, mean arterial pressue, heart rate) and measuredd values (maximum diameter of vena cava inferior, minimum diameter of vena cava inferior, central venous pressure, PVI, CO, and stroke volume) were recorded. After applying crystalloid in a dose of 10 mL/kg for 15 minutes, the recorded parameters were repeated at 15th minute. Results: When receiver operating characteristic (ROC) analysis was performed for dIVC, the area under the curve (AUC) was found to be 0.833 (0.739-0.926). The threshold value was found to be 17.52%, sensitivity was 77.5%, and specificity was 72.5%. When ROC analysis was performed for PVI, AUC was found to be 0.889 (0.817-0.962). The threshold value was found as 12.50%, sensitivity was 72.5%, and specificity was 92.5%. Conclusion: PVI was found to be more specific but less sensitive than dIVC. dIVC is less sensitive and less specific than central venous pressure. However, dIVC and PVI can give useful results in patients who have contraindication of an invasive technique.