 Acute renal failure is common among the critically ill 1-3 , and is an independent contributor to morbidity and mortality 4,5. Continuous renal replacement therapy CRRT is commonly used for renal replacement in this group. This requires an extracorporeal circuit, the maintenance of which requires anticoagulation. Heparin has been the most common anticoagulant used with CRRT. However, heparin exposure for CRRT is major risk after surgery or trauma. Citrate has been used as a regional anticoagulant for plasmapheresis and chronic dialysis for many years 12,13, and is increasingly being used for CRRT. Regional anticoagulation refers to the provision of anticoagulation within the extracorporeal circuit without any alteration in coagulation in the patients systemic circulation. Calcium is a co-factor in coagulation. Citrate reduces levels of ionized calcium in blood of the extracorporeal circuit to levels where coagulation cannot occur. Once the blood is returned to the patients systemic circulation, the calcium levels are restored and coagulation can occur again. Renal replacement solutions for CRRT using citrate anticoagulation, should be calcium-free. 14-19 Despite a reduced risk of bleeding, widespread adoption of citrate regional anticoagulation has been limited by a lack of commercially available calcium-free solutions and the complexity of many protocols. Part of this complexity is the requirement for a separate citrate infusion into the extracorporeal circuit to achieve regional anticoagulation. This simplified protocol provides citrate in the replacement fluid infused prefilter as both anticoagulant and as buffer. 