Splenectomy leads to an increased susceptibility to infection. We have investigated the uptake and functional value of autotransplanted spleen grafts that were reimplanted into the omentum of rabbits undergoing splenectomy. Nine rabbits underwent splenectomy (Group A), and nine rabbits underwent splenectomy with the resected spleen sliced and reimplanted into the omentum (Group B). Six additional rabbits, the control group, were sham-operated only. The functional value of the reimplanted splenic tissue was determined by a follow-up on serum IgM levels, the presence of Howell-Jolly bodies in peripheral blood smears (every alternate week), and a Technetium phytate scan and histopathological examination of the implanted tissue 20 weeks after the operation. During the study, three animals of Group A and five of Group B died from septic complications. No deaths occurred in the control group. Twenty weeks postoperatively, the reimplanted group had normal IgM levels and positive implanted splenic tissue scans, and lacked Howell-Jolly bodies in the blood. These findings indicate that the splenic autotransplants in the omentum were viable, showed phagocytic activity, and produced immunological proteins.