DISEASE CHARACTERISTICS: Cytologically confirmed myelodysplastic syndrome (MDS) Increased blasts (i.e., greater than 1 to 30% peripheral blood blasts and/or 5 to 30% bone marrow blasts) AND International Prognostic Score intermediate 1, intermediate 2, or high risk Refractory anemia with excess blasts OR Refractory anemia with excess blasts in transformation (no presence of auer rods as sole criteria) OR Chronic myelomonocytic leukemia Greater than 1% blasts in the peripheral blood and/or at least 5% blasts in the bone marrow OR MDS related acute myeloid leukemia Arising after documented MDS of at least 60 days Absolute peripheral blast count no greater than 5,000/mm3 Must have genotypically HLA identical sibling donor Must also be enrolled on SWOG-S9910 and SWOG-9007

PATIENT CHARACTERISTICS: Age: 16 to 55 Performance status: Zubrod 0-2 Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Not specified Renal: Not specified Other: No prior malignancy within past 5 years except: Adequately treated basal cell or squamous cell skin cancer Carcinoma in situ of the cervix Adequately treated stage I or II cancer in complete remission HIV negative Not pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No autologous peripheral stem cell transplantation prior to diagnosis of myelodysplastic syndrome (MDS) or MDS related acute myeloid leukemia Chemotherapy: No prior chemotherapy for MDS or MDS related acute myeloid leukemia except oral chemotherapy to control leukocytosis or thrombocytosis (e.g., hydroxyurea or etoposide) Endocrine therapy: Not specified Radiotherapy: No radiotherapy prior to diagnosis of MDS or MDS related acute myeloid leukemia Surgery: Not specified