The concentration of factor VIII and partial thromboplastin times became normal and have remained normal for 140 days after orthotopic tranplantation of a normal liver to a hemophilic dog. Transplantation of a normal spleen into a hemophilic recipient did not result in a significant increase in factor VIII although the splenic graft was viable for at least 47 days. Transplantation of normal marrow to a lethally irradiated hemophilic dog did not result in an increase in factor VIII during 34 days of observation.