Aim: Acute renal failure (ARF) after hematopoietic stem cell transplantation (HSCT) is a widespread complication leading to considerable morbidity and mortality. The present study aims to determine the incidence and risk factors of ARF and to investigate whether there exists a relationship between the renal injury indicators and quantity of the transplanted stem cells in a uniform patient population after allogeneic myeloablative HSCT. Methods: Patients undergoing myeloablative allogeneic HSCT from 2007 to 2008 were monitored prospectively in terms of their renal functions during the first 100 days after transplantation. ARF was defined as a twofold rise in serum creatinine concentration of baseline value or a >50% decrease in creatinine clearance and classified into three grades. Results: ARF occurred in 51.3% of patients over a period of 100 days after HSCT. ARF developed in 12 (60.0%) patients within the first 2 weeks, whereas in 8 (40.0%) of them ARF development was observed within 2-4 weeks. No correlation was found between ARF development and the quantity of the infused hematopoietic stem cells. Additionally, we were not able to identify a particular cause which was significantly associated with the occurrence of ARF after HSCT. Conclusion: A 51.3% incidence of ARF was found in patients after myeloablative allogeneic HSCT. ARF in HSCT patients could not be linked to a single cause. Rather a combination of multiple risk factors seems to be responsible for ARF development.