Abstract Background and Aims Orthotopic liver transplantation (OLt) is a technically complex surgical procedure associated with a major risk of hemodynamic instability and metabolic derangement, especially in patients with coexisting renal dysfunction. It remains uncertain if intraoperative renal replacement therapy (ioRRT) during OLt could be beneficial and in which subset of patients. Method A retrospective observational study of all adult patients undergoing intraoperative renal replacement therapy during OLt in our center from January 2010 till December 2018. IoRRT consisted of dialysis performed with the use of mobile Genius® single-pass batch dialysis system. Results 1319 OLts were conducted during the study period and 129 patients (9,8%) were treated with intraoperative dialysis. Seven patients with incomplete documentation were excluded from the study. The mean age of the cohort was 47,8±14,7 years, and 73 (60%) of patients were men. The mean calculated MELD score was 33,7±12,5. 41 procedures (33,6%) were retransplantations and 7 patients underwent simultaneous liver and kidney transplantation. 18 (14,7%) recipients had fulminant liver failure. 66 (54,1%) of patients were admitted to Intensive Care Unit before transplantation. The mean preoperative serum creatinine level was 2,95±1,15 mg/dl and 95 (78%) patients were undergoing renal replacement therapy or had creatinine level ≥2 mg/dl preoperatively. Others required emergent ioRRT due to intraoperative complications and development of significant hyperkalemia or acidosis. The mean preoperative serum potassium concentration was 4,23±0,68 mmol/l and the mean bicarbonate level was 19,8±4,5 mmol/l. Intraoperative dialysis was performed without anticoagulation. The mean surgical time was 400±90,6 minutes and the mean ioRRT duration remained 308 ±109 minutes. Dialysis circuit clotting occurred in 9 (7,3%) cases. There were no other adverse events of ioRRT. Achieved mean arterial bicarbonate and potassium levels after graft reperfusion were 18,5±3,6 and 3,8±0,95 mmol/l, respectively. In 111 cases dialysis was initiated at least 15 minutes before reperfusion. 13% of this subgroup (16 pts) experienced post-reperfusion syndrome (defined as a decrease in the mean arterial pressure of more than 30% of the baseline, occurring within first 5 minutes after the reperfusion of the graft and lasting at least 1 minute). Conclusion Our data suggests that intraoperative dialysis in severely ill patients with high MELD score is safe and effective. Lower than expected post-reperfusion syndrome occurrence needs to be confirmed in a study designed with appropriate control group.