Acute myeloid leukemia (AML) is the most common type of leukemia among the elderly. Lymphocytes of approximately 55% of AML patients show various chromosomal aberrations, including structural and numerical alterations. Such changes may not only correlate with morphological and clinical data, but also serve as prognostic factors. We describe the case of AML patient with complex karyotype examined by means of array CGH. The number of aberrations found was significantly higher as compared with GTG results, which indicates that aCGH enables more sensitive karyotype examination and may be used in the search for new prognostic and predictive factors in AML.