Autologous splenic tissue was implanted in 14 patients undergoing splenectomy for traumatic rupture or peroperatively arising lesion of the spleen. To demonstrate function of the implanted splenic tissue, spleen scintigraphy using 99mTc-labelled heat-damaged autologous erythrocytes, and percentage measurement of vacuolated erythrocytes in peripheral blood were performed one and three months after the splenectomy. The spleen scans were positive in eight patients after one month and in 12 patients after three months, demonstrating splenic phagocytic function. The numbers of vacuolated erythrocytes also indicated some restoration of the pitting function due to the implanted splenic tissue. No alterations were seen in serum immunoglobulins, but a moderate thrombocytosis still persisted after three months. The clinical significance of implantation of autologous splenic tissue is discussed.