De novo acute myeloid leukemias (AML) represent a heterogeneous group of clonal hematopoietic disorders in which chromosomal abnormalities are detected in a majority of patients. At present, cytogenetic changes are recognized as important diagnostic markers and prognosis determinants. Complex karyotype changes are associated with resistance to treatment and unfavorable evolution. We report on an AML case with complex karyotype changes characterized by molecular genetic techniques (fluorescence in situ hybridization - FISH and array-based comparative genomic hybridization - array-CGH) and an extremely poor outcome. A 72 year-old female patient was admitted for genetic investigations with a clinical diagnosis of AML. Classical and molecular cytogenetic tests as well as array-CGH were performed. Complex chromosomal abnormalities were identified at diagnosis, consisting of genomic imbalances involving chromosomes 6, 7, 9, and 17. AML with complex karyotype changes is a heterogeneous disease, as a variety of genomic abnormalities are detected, involving virtually all chromosomes. The pathogenesis of AML with complex karyotype is poorly understood. The complexity of karyotypic changes in our case highlights the importance of using complementary genetic investigation in order to obtain a comprehensive view of AML genome.