Acute Myeloid Leukemia (AML) is associated with 10-15% of allmalignant tumors of the hematopoietic system in children. Its majorcharacteristics include uncontrolled growth of immature white bloodcells (excluding lymphocytes), erythroblasts and megakaryoblasts.Generally, current treatment strategies lead to complete remission ofthe neoplasm in about 75% of cases, though for AML sucha remission is observed only in ~50% of children. Experiments andanalyses conducted within this study focused mainly on the presenceof the most frequently occurring genetic markers of the disease(Internal Tandem Duplications, ITD within the FLT3 gene) orpotential markers for minimal residual disease (MRD); these includedpresence of pathological mRNA transcripts arising from chromosomalrearrangements (i.e. AML1-ETO [t(8;21)], PML-RARα [t(15;17)] andCBFβ-MYH11 [inv16]). Special consideration was given to alterationsin the WT1 gene expression levels and polymorphisms within theWT1 gene. Current study included 69 children (53.1%) aged 0.2-18.5years (median of 11.2 years), selected from the primary AML group(n=130; admission time: 01.03.2006-31.06.2009; from 14 PPLLSGcenters). Bone marrow and/or peripheral blood samples were collectedfrom each subject at least one year before the commencement of thetreatment. All patients were treated according to AML-BFMINTERIM 2004 programme.