SummaryThe purpose of this prospective observation cohort study was to develop and validate a risk stratification model for prediction of acute renal failure after liver transplantation. Data from 71 orthotopic liver transplantation recipients were used to develop a risk stratification model by binary logistic regression analysis containing the following variables: pretransplant hepatitis B and ⁄ or C infection; arterial hypertension; intra-operative mean arterial blood pressure before induction of anaesthesia; units of packed red blood cells required; hypotension (mean arterial blood pressure £50 mmHg); and maximum lactate concentration. Validation of the model on 167 consecutive patients revealed a sensitivity of 0.78, a specifity of 0.92, a negative predictive value of 0.96 and a positive predictive value of 0.62. This risk stratification model enables identification of orthotopic liver transplantation recipients with no or low risk for acute renal failure directly at the end of the transplantation procedure. Acute renal failure is a common and severe complication after major surgery and organ transplantation. In a population-based cohort analysis including 69 321 patients after non-renal organ transplantation, 7.6% of the patients developed postoperative acute renal failure (defined by 50% reduction in glomerular filtration rate or a need for urgent dialysis) [1]. Previous estimations of the incidence of acute renal failure after orthotopic liver transplantation in adults vary between 31% and 94%, depending on the definition used [2][3][4][5][6]. Its multifactorial origin complicates the identification of risk factors to develop prevention strategies. Acute renal failure can occur early in the postoperative course and seems to be related to pre-operative conditions and to the operative procedure. Impaired renal function and especially the need for post-transplant renal replacement therapy is associated with prolonged hospitalisation, increased mortality [2,[7][8][9], and significant financial cost [10].These observations prompted this prospective observational study, with the aim of developing a prediction model to identify patients at risk for acute renal failure requiring renal replacement therapy directly at the end of the transplantation procedure. Therefore we investigated only pre-and intra-operative risk factors for the development of acute renal failure after orthotopic liver transplantation, postoperative risk factors such as nephrotoxic drugs or postoperative complications having been extensively studied in the past.