Main purpose of the study : treatment ( Role of early hemodialysis on acute kidney injury in critically ill patients ) . Study design: interventional, non-randomized, double blind and parallel without placebo. Target sample size: 60 patients from both sexes between ages 18 and 60. If there is one of the following scales such as , at least 50% creatinine rise from the admission time , BUN>70, oliguria <0.5 ml/kg/h for 12 hours with no response to volume and Furosemide , anuria <0.3 ml/kg/h for 6 hours with no response to volume and Furosemide, will be specified as Early Hemodialysis Group (D) and if there is criteria such as volume overload ( pulmonary edema) , BUN>100 or occurance of azotemia complications (ex:loss of Consciousness ) and cr>4 will be specified as Group C. In case of oliguria (U/O<0.5 ml/kg/h) or aniria (U/O<0.3 ml/kg/h or cessation of urine ), infusion of 500 ml crystalloid with 60 mg Furosemide in 1 hour will be administered and while there is no response , the patient entered the study. Exclusion criteria: history of renal insufficiency , reception of high dose inotropics, septic shock , severe electrolyte abnormalities leading to hemodialysis. Intervention: hemodialysis central vein catheter will be inserted for the patients and dialysis will start daily ( 2 hours for the first day then 4 hours). Dialysis will be done at least for 3 days and in case of appropriate urination , correction of urea or creatinine, dialysis implementation will be every other day for about 3 hours. When the blood urea and creatinine are stabled, the dialysis is suspended and restarting is according to mentioned indications. Primary outcome measure: plasma creatinine,blood urea and urine volume. Secondary outcome measure : length of stay and mortality rate in intensive care unit.