BACKGROUND Identification of risk factors of acute renal failure (ARF) after orthotopic liver transplantation (OLT) may avoid the development and attenuate the impact on patient outcome. Therefore, the incidence and risk factors of ARF after OLT at Siriraj Hospital were analyzed. METHODS The study was retrospectively analyzed from the OLT patients at the Siriraj Hospital between January 2002 and December 2009. ARF was defined as an increased in serum creatinine level more than 1.5 times within the first week postoperation compared with the preoperative level. RESULTS A total of 81 liver transplant patients were analyzed. The mean age was 52.45 years (range, 22 to 71) and there were 25 women (30.86%) and 56 men (69.14%). Indications for OLT were end-stage liver cirrhosis (n = 43, 53.09%), hepatocellular carcinoma (n = 36, 44.44%), and fulminant hepatic failure (n = 2, 2.47%). Fifty-eight patients (71.60%) developed ARF, and the perioperative mortality of these was 18.97%. The univariate analysis identified the presence of preoperative coagulopathy, prolonged intraoperative hypotension, more blood loss, and postoperative hypotension as the risk factors of ARF. By the multivariate analysis, prolonged intraoperative hypotension more than 30 minutes and presence of postoperative hypotension were the independent risk factors of ARF. During the intraoperative and postoperative periods, ARF group required more blood and blood components transfusion, longer intensive care unit stay, and higher in-hospital mortality. Seven patients (12.07%) in the ARF group required postoperative renal replacement therapy. Four patients (9.52%) developed chronic renal failure, and one of them required long-term hemodialysis. CONCLUSIONS ARF was a common complication after OLT, which caused increased morbidity and mortality. Although some patients required dialysis, most of them recovered normal renal function. Prolonged intraoperative hypotension and presence of postoperative hypotension were the independent risk factors of ARF after OLT.