Severe factor XI deficiency (hemophilia C) is a rare coagulation disorder. A 73-year-old woman, a homozygote for factor XI deficiency, required aortic valve replacement. An initial dose of 15 U kg of factor XI concentrate was administered preoperatively and on postoperative day 3. During surgery, concentrated red cells, fresh frozen plasma, platelets, tranexamic acid, and fibrinogen were transfused. Intraoperative bleeding and total chest drainage were minimal. Postoperatively, there was no need for further transfusions and no bleeding or thrombotic complications occurred. The patient was well 16 months after surgery.