A congenital factor VII deficiency is a rare disorder with an estimated incidence in the western contries of one in 500, 000. Because factor VII is important in initiation the coagulation cascade, a factor VII deficiency can result in significant bleeding with prolongation of the prothrombin time. We present a case of a factor VII deficiency with a subdural hematoma in an 18-year-old boy whose plasma activity of factor VII was < or =10%. Previously, he did not have any symptoms, such as hemarthrosis, easy bruising or bleeding after a minor trauma. He was administered fresh frozen plasma and a trephination was performed. His sister also had 51% lower level of factor VII.