A 61-year-old woman with chronic myelogenous leukemia (CML) in accelerated phase had a near-triploid bone-marrow karyotype. This karyotype is an unusual finding in CML, as we review 12 previously published similar cases. These patients do not differ clinically from other patients with CML in blast crisis. The cytogenetic features of near-diploid and near-triploid CML are similar, except that relative loss of chromosomes is more common and that isochromosome 17q has not been reported in near-triploid CML.