Complex cardiac surgery often requires blood transfusion. Some patients refuse transfusion, even when it is potentially life-threatening to do so. Although recombinant human erythropoietin (rhEPO) has been used to reduce the need for blood transfusion, it has been considered ineffective in critically ill patients. The time course of hematological responses in a Jehovah's Witness patient with acute renal failure and severe cardiac disease suggests that a trial of rhEPO should be considered for salvage therapy in critically ill patients. CONCLUSIONS The authors describe successful treatment of life-threatening anemia using recombinant human erythropoietin in a critically ill Jehovah's Witness patient after cardiac surgery.