It has been common practice for dialysis patients with problematic vascular access to receive warfarin for the purposes of keeping the access functional. This, of course, increases the risk for bleeding. Also, in light of new knowledge, vascular calcification may be enhanced by warfarin (1). Therefore, a reexamination of this common practice seems warranted because the efficacy of anticoagulation for access maintenance has never been established. The available evidence does not allow an evidence-based approach. Therefore, this article is an opinion, based on what is published. The issue obviously warrants a prospective study because the clinical practice is widespread. The most common indication for prescribing warfarin in hemodialysis patients is to maintain vascular access. In dialysis patients with comorbid rhythm disturbances such as atrial fibrillation or patients with prosthetic valves, warfarin may be indicated to prevent stroke. The benefit/harm ratio for this indication needs to be considered separately because the efficacy of warfarin to prevent thromboembolism is well established. A small percentage of warfarin use in ESRD is in patients who have documented hypercoagulable states. The major risk of warfarin in dialysis patients obviously is bleeding, adding to the already present uremic platelet dysfunction that accompanies progressive chronic renal disease. Another major issue regarding warfarin use in dialysis patients is potential bleeding in the event of unplanned or emergency surgery, such as in patients who are awaiting deceased-donor renal transplant. In these cases, surgery may be necessary before the warfarin can be withdrawn. In this situation, even fresh-frozen plasma and vitamin K do not fully reverse the patient’s anticoagulation. In the general population, a rare complication of warfarin is dramatic skin necrosis, presumably as a result of vitamin K deficiency. Risk factors for this adverse reaction are proteins C and S deficiencies and diffuse vascular disease. Because protein S frequently …