From 1969 to 1985 we discovered accessory spleens in 8 patients with chronic immune thrombocytopenic purpura (ITP) who relapsed or failed after splenectomy. Imaging of accessory spleen used a liver spleen scintigraphy with heat-treated RBC labeled with Tc-99m. Platelet kinetic studies with 51Cr or 111In, including sequestration index, were performed. Five patients had accessory splenectomy. Disappearance of bleeding symptoms was achieved in the 5 splenectomized patients but with only partial response of platelet counts. These results are discussed in the context of diagnosis and therapeutic management of accessory spleens in patients with chronic immune thrombocytopenic purpura who relapsed or failed after splenectomy.