Hemophilia is a hereditary bleeding disorder caused by deficient or defective clotting factors, mainly factor VIII (hemophilia A) and factor IX (hemophilia B). These deficiencies are due to mutations on the X chromosome and thus are X-linked recessive traits. Patients present with bleeding symptoms like hemarthroses, muscle bleeds, or CNS hemorrhages that are out of proportion to any injury. Diagnosis involves identifying prolongation of activated partial thromboplastin time and deficient specific clotting factor levels. Treatment focuses on replacement of the missing clotting factor through infusion of factor concentrates.