Hematological malignancies in Jehovah's Witnesses are often difficult to cure since these patients deny transfusions. By a retrospective analysis, we report the possibility of treating some tumors, mostly hematological, with either autologous or allogeneic bone marrow transplantation (BMT) without blood support. Eight patients were evaluated, including lymphoma (two patients), acute lymphoblastic (one patient) and myeloblastic (one patient) leukemia, chronic lymphocytic leukemia (one patient), refractory anemia with blasts in transformation (one patient), chronic myeloid leukemia (one patient) and metastatic breast cancer (one patient). All patients experienced a severe cytopenia with no major side effects or life-threatening complications. We had four deaths: three from relapse and progression of the disease (at 5, 8 and 15 months after the stem cell infusion), and one from acute intestinal GVHD (at 2 months after the stem cell infusion). Four patients are in complete clinical remission (at 8, 10, 16 and 26 months after the stem cell infusion), and this was related to the disease outcome. We conclude that autologous and allogeneic BMT are feasible without the support of transfusions. We believe that this should be performed as soon as possible in the course of the disease.