Six cases of iliopsoas hematoma were diagnosed in 5 patients with hemophilia over the last 5 years at our hemophilia center. We reviewed these cases to determine the incidence and precipitating factors of iliopsoas hematoma in hemophilia. Of the 5 patients, 4 had severe hemophilia A and 1 had moderate hemophilia A with a history of inhibitors to factor VIII concentrates. The age range was 13 to 33 years. The hematoma was posttraumatic in 2 cases and spontaneous in 4 cases. Femoral nerve compression developed in 2 cases. There were four recurrences. At the time of the hematoma, 2 patients were receiving long-term prophylactic factor VIII concentrate therapy but one of them had stopped the injections of his own accord. The treatment consisted of recombinant factor VIII concentrates, a brief course of glucocorticoid therapy in the 2 cases with femoral nerve involvement, lower limb traction in 3 patients, and rehabilitation therapy. The annual incidence rate of iliopsoas hematoma was 2.9/1000 patients with severe or moderate hemophilia A. The use of prophylactic factor VIII therapy and compliance with recommendations about avoiding activities that put strain on the hip flexor muscles probably explain the low rate of iliopsoas muscle hematoma in patients with hemophilia in France. An early diagnosis allows early Factor VIII therapy, which decreases the risk of femoral nerve involvement and recurrence.