Renal allografts were transplanted into 20 dogs (12 beagles, eight mongrels) following a prescribed protocol for pre-transplantation blood transfusions and kidney exchange. Immunosuppressive therapy (azathioprine and prednisone) was modified as needed for each dog. Seven of the beagle dogs survived for 1 year and were then euthanized; all other dogs died or were euthanized prior to 1 year post-transplantation. Graft rejection and renal failure were the greatest causes of mortality. Renal lesions which contributed to the death of some animals included renal vein thrombosis, nephrosis, and pyelonephritis. Inflammation of the lower respiratory tract (bronchitis, pneumonia, and pleuritis) was a contributory cause of death in some dogs. Cystitis and ureteritis occurred in almost half of the dogs. Prostatitis was seen in six of the 16 male dogs. Adrenal cortical atrophy, parathyroid gland hyperplasia, and bone marrow hypocellularity were seen in a majority of the dogs which survived 1 year.