Canine recipients were given three preceding transfusions of irradiated whole blood from DLA-identical marrow donors on days -24, -17, and -10. 211-At-labeled anti-CD45 mAb was given on day -3. TBI (9.2Gy) and bone marrow were given on day 0. Blood counts and chemistry were analyzed on days -7, -3, 0. They were evaluated daily until full hematopoietic recovery, then, once a week until the end of study.