Even though hyperdiploidy is not a rare finding in advanced phase-CML, hyperdiploidy together with a T315I kinase domain (KD) mutation in the BCR-ABL gene has not yet been reported.<h4>Results</h4>A complete cytogenetic and molecular cytogenetic analysis; molecular biology methods such as quantitative reverse transcription polymerase chain reaction (RQ-PCR) and allele-specific oligonucleotide (ASO)-PCR; and immunophenotypically confirmed CML in acceleration phase (AP). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.