BACKGROUND: Intradialytic hypotension is a serious complication during renal replacement therapy in critically ill patients. Early prediction of intradialytic hypotension could allow adequate prophylactic measures. In this study we evaluated the ability of peripheral perfusion index (PPI) and heart rate variability (HRV) to predict intradialytic hypotension. METHODS: A prospective observational study included 36 critically ill patients with acute kidney injury during their first session of intermittent hemodialysis. In addition to basic vital signs, PPI was measured using Radical-7 (Masimo) device. Electrical cardiometry (ICON) device was used for measuring cardiac output, systemic vascular resistance, and HRV. All hemodynamic values were recorded at the following time points: 30 min before the hemodialysis session, 15 min before the start of hemodialysis session, every 5 min during the session, and 15 min after the conclusion of the session. The ability of all variables to predict intradialytic hypotension was assessed through area under receiver operating characteristic (AUROC) curve calculation. RESULTS: Twenty-three patients (64%) had intradialytic hypotension. Patients with pulmonary oedema showed higher risk for development of intradialytic hypotension Odds ratio (95% CI): 13.75(1.4-136). Each of baseline HRV, and baseline PPI showed good predictive properties for intradialytic hypotension AUROC (95% CI): 0.761(0.59-0.88), and 0.721(0.547-0.857) respectively. CONCLUSIONS: Each of low PPI, low HRV, and the presence of pulmonary oedema are good predictors of intradialytic hypotension.