This is a man in his late 70s with a history of myocardial infarction and congenital factor XI (FXI) deficiency, who underwent urgent coronary artery bypass surgery for coronary artery disease. He demonstrated less than 2% factor XI activity on serological assay. Preoperatively, the patient was managed with only a non-therapeutic heparin drip, forgoing any preoperative factor resuscitation. Intraoperatively, the patient received fresh frozen plasma administration for post-bypass coagulopathy based on real-time assessment of bleeding. This resuscitation strategy advocates for the use of factor products based on clinical assessment as opposed to prophylactic resuscitation. Further research is required on the appropriate resuscitation strategy for FXI deficiency in the cardiac surgery patient. Practitioners should select a protocol that accounts for deficient factor XI levels, coagulopathy associated with cardiopulmonary bypass and the volume status of the patient.