The authors report a rare case of an acute cerebral aneurysm rupture in a patient with a known factor XI deficiency. Aneurysmal subarachnoid hemorrhage (SAH) accounts for a high mortality and morbidity rate. When SAH is associated with an inherited coagulation disorder such as hemophilia C, an unexpected and possible increase in hemorrhagic stroke and increase in bleeding during surgery and in the postoperative period could lead to an extremely bad outcome. Clinical management consists of rapid correction of the coagulation disorder before undergoing any invasive intracranial procedure. Such an optimal therapeutic strategy must be under the care of a multidisciplinary medical and surgical team. Human factor XI concentrate (Hemoleven, Laboratoire Français du Fractionnement et des Biotechnologies [LFB], Les Ulis, France) was used successfully in this case report. New treatment using recombinant factor VIIa is discussed.