DISEASE CHARACTERISTICS: Primary or secondary acute nonlymphocytic leukemia and acute lymphocytic leukemia in one of the following states: First or greater remission Early relapse Chronic myelogenous leukemia (CML) in one of the following states: First or greater chronic phase Treatment on this protocol is preferred to total body irradiation containing protocols for patients under 40 with CML in stable first chronic phase who are otherwise eligible for allogeneic bone marrow transplantation Accelerated phase Myeloid or lymphoid blast crisis Myelodysplastic syndromes of the following types: Refractory anemia Refractory anemia with ringed sideroblasts Refractory anemia with excess blasts Chronic myelomonocytic leukemia Multiple myeloma Non-Hodgkin's lymphoma HLA identical bone marrow donor available Unable to undergo total body irradiation because of one of the following reasons: Under age 2 (CNS still growing and at high risk of permanent radiation injury) Prior high dose radiotherapy to the brain, lungs, heart, liver, or abdomen In relapse following allogeneic or autologous transplant using total body irradiation for ablation, but eligible for a second transplant No current CNS involvement