In the last five year, 198 critic patients developed acute renal failure, requiring hemodialysis in the hospital. We realized a descriptive study and analyzed the factors that were statistically associated with higher mortality: a surgical etiology, clinic criteria for the inicial of hemodialysis, respiratory failure, hemodynamic inestability, hepatic insufficciency, disseminated intravascular coagulacion and oliguric or anuria. The sepsis and the cardiorrespiratory complications were the cause of mortality most important. The 14% of the surviving requiring continue in the programs of hemodyalisis.