DISEASE CHARACTERISTICS: The following hematologic malignancies are eligible: Acute nonlymphocytic leukemia in one of the following categories: In complete remission In early relapse Newly diagnosed FAB types M6 and M7 Myelodysplastic syndromes including: Refractory anemia with excessive blasts Refractory anemia with excessive blasts in transformation Chronic myelomonocytic leukemia Secondary acute myeloid leukemia Transplantation priority given in decreasing order of: First remission Second remission Third remission Early relapse, with priority further reduced for: Refractory response to platelet transfusion Severe infection within 6 weeks prior to referral History of major organ pathology or insult (hepatitis, renal damage, pulmonary disease, cystitis, etc.) CNS disease allowed but priority status for transplantation lowered Donor Criteria: Sibling or matched related/unrelated donor required Donor priority as follows: Monozygotic twin Genotypical or phenotypical HLA-A, -B, -C, and -D match Match at any 2 loci (A, B, Dr) on the other haplotype ABO-compatible donor preferred Marrow processed to eliminate mismatched erythrocytes if ABO incompatible In case of multiple donors, priority is: ABO compatibility Age over 18 Same sex No physiologic, psychologic, or medical contraindication to donation procedure No increased anesthetic risk due to pre-existing illness HIV negative