DISEASE CHARACTERISTICS: Advanced chronic lymphocytic leukemia (Rai stage 3 or 4) with at least one of the following high-risk factors: Beta-2 microglobulin 3 or greater Abnormalities of chromosome 17 Other cytogenetic abnormalities Refractory to fludarabine-based chemotherapy or failure to achieve complete remission after 6 courses of a fludarabine-based regimen HLA-identical sibling donor willing and able to undergo apheresis for harvest of G-CSF-stimulated peripheral blood stem cells