Autoimmune cytopenias are rare but serious complications after hematopoietic stem cell transplantation (HSCT). We performed splenectomy in 2 patients who had severe autoimmune cytopenias after allogeneic HSCT (allo-HSCT) that were resistant to immunosuppressive treatment. The first patient underwent unrelated allo-HSCT for chronic granulocytic leukemia (CGL) in July 2000. Seven months later, red blood cell and platelet counts went down. The results of a direct Coombs test were intermittently positive. The patient was resistant to therapy with steroids and high-dose immunoglobulin. After a splenectomy was performed in February 2001, the hemoglobin concentration and platelet count improved. Her blood counts remained stable, with a hemoglobin level of approximately 110 g/L and a platelet count > 100 X 10(9)/L. She continued therapy with itra-conazole, valacyclovir, and penicillin. Some months later, the patient was readmitted for fulminant septic infection, which had a fatal outcome. The second patient underwent related allo-SCT for CGL in January 2003. Seven months later, he was readmitted for intraocular bleeding accompanied by severe thrombocytopenia with antiplatelet antibodies. The patient was resistant to steroid and high-dose immunoglobulin therapy. A splenectomy was performed in September 2003. His platelet count normalized and remains stable. The patient continues therapy with itra-conazole, valacyclovir, and penicillin and has not experienced any serious infection. We assume that splenectomy is an effective treatment for resistant immune cytopenias after allo-HSCT. However, severe late infections can compromise the outcome.