Background/Aims: Coronary artery bypass grafting (CABG) is associated with an increased risk of morbidity and mortality in patients with pre-existing renal dysfunction. Numerous measures have been implemented to overcome this problem; however, no improvement in outcomes has been achieved. This study was aimed at investigating the effects of prophylactic dialysis on mortality and morbidity in these patients. Methods: This randomized-controlled clinical trial enrolled 88 non-dialysis-dependent patients with chronic kidney disease awaiting CABG surgery. Thirty-nine randomly selected patients received dialysis 3 times prior to surgery, and 49 patients formed the control group. Kaplan-Meier analysis and Cox proportional-hazards models were used to identify factors associated with survival. Results: There was no significant difference in the development of morbidities between the groups (p = 0.413). A significant difference was evident in the average survival time (p = 0.037). Cox proportional-hazards models determined that the hazard ratio of death after surgery was 10.854-fold greater in non-dialysis patients than in patients who received dialysis (hazard ratio = 2). Conclusion: Prophylactic dialysis prior to CABG decreases mortality, but does not affect morbidity, in patients with renal insufficiency.