To prevent postsplenectomy overwhelming sepsis, splenic autotransplantation has been clinically attempted. However, function of regenerated splenic tissue after splenic autotransplantation has not been completely understood. Changes in weigh of regenerated splenic tissue, splenic blood flow, splenic immune responses and phagocytic function were studied for one year after splenic autotransplantation using Sprague-Dawley rats. At one year after autotransplantation, the weight of regenerated splenic tissue was increased to 80% of the originally implanted spleen and the blood flow was increased to 80% of the control spleen. The counts of lymphocytes and macrophages in the regenerated splenic tissue were significantly low at eight weeks after transplantation, however lymphocytes was increased to 58.8% and macrophages was increased to 29.5% of the control spleen at 16 weeks after transplantation. The blast formation of splenic lymphocytes was lower at the early stage after transplantation, thereafter, it was increased at the later time after transplantation. Microangiography of the regenerated spleen showed new capillaries around the implanted tissue 2 weeks after transplantation. These results suggested that the transplanted splenic tissue was regenerated to the similar structure to normal spleen and immunological function was recovered close to the normal splenic tissue.