This report describes the clinical findings of a British shorthair cat with hemophilia B, the family pedigree surrounding the case, and how this disorder can be perpetuated in rare breeds of cats that may be inbred by necessity. Young cats with histories of bleeding episodes following elective or other surgical procedures, periodic shifting lamenesses, or the development of subcutaneous hematomas should be suspect for an inherited coagulation disorder. Hemophilia A (factor VIII deficiency) or hemophilia B (factor IX deficiency) are the most likely causes, although other inherited bleeding disorders also have been recognized in cats.