Critically ill patients with acute renal failure who are receiving dialysis therapy may suffer from many complications that can be decreased by using bicarbonate dialysate during dialysis sessions. Aim: this study was carried out to compare between the hemodialized acute renal failure patientsusing bicarbonate versus acetate dialysate ondeveloping complications. Design: descriptive comparative designutilized in this study. Setting: This study was carried out at the kidney dialysisunit, Assiut University Hospital. Subjects Sixty adult male and female critically ill patients with acute renal failure who are admitted to the kidney dialysis unit (how many using bicarbonate and how many using acetate and how you selected them).Tool:“hemodialysis patient observational and monitoring tool” was used to monitor and record the personal and medical data needed for this study by the researcher.Methods: Interview, observation and reviewing patient`s records were utilized to collect data pertinent to the study. Each patient was monitored closely ten minutes before connection to the dialysis machine, during the dialysis session and ten minutes after disconnection, three times per week for two successive weeks. Results: The patients on the acetate group had experienced many problems (tachycardia, hypotension and dyspnea). There was a significant statistical difference between both groups with (p value=0.001). Conclusion: the group of patients on bicarbonate dialysate during dialysis sessions was found to experience lesser problems than acetate dialysis group.