Renal allografting was performed between DLA-identical beagle littermates without immunosuppressive treatment. One transfusion of 200 ml of parental blood was given 14 days prior to transplantation. A parent of the kidney donor and recipient was chosen as blood donor to induce the formation of antibodies against non-DLA antigens that might enhance renal graft survival. Kidney graft survival times of transfused dogs were compared with the survival times of DLA-identical nontransfused littermates. Blood transfusions did not have a significant influence on the median graft survival time. Antibodies against the kidney donor lymphocytes were not demonstrated after blood transfusions. However, antibodies were induced in three of the six animals tested as shown by the reactivity of the sera of these animals against a lymphocyte panel. Antibodies occurred in animals with long-term as well as short-term surviving grafts.