The GATA-4, -5 and -6 group of genes is characterized by its role as proliferation and differentiation regulators in endodermal and mesodermal tissue. Despite indications of GATA-4 and -6 involvement in hematopoiesis, up until now only methylation analyses of the GATA-4, -5 and-6 transcription factors exist in solid tumors. As such, on the basis of MSP analyses, the present study offered the interesting possibility of examining the relevance of aberrant promoter methylation of the GATA-4, -5 and -6 transcription factors in the pathogenesis of AML (acute myeloid leukemia). Aberrant methylation of the GATA-4 promoter region was detected in 20.5% of the 73 AML patient samples. The methylation frequencies of the GATA-5 and -6 promoter regions were 1.4% and 2.7%. The GATA-4 methylation frequency, which was the highest with 20.5%, suggests that methylation-caused inactivation of GATA-4 increases the differentiation blocking of myeloid blast cells and as such may contribute to the malignant transformation of hematopoietic cell clones in AML. The FAB subtypes M1 and M4 mostly feature an unmethylated GATA-4 promoter region. This means that here, epigenetic modification of GATA-4 seems to have less pathogenic significance. Furthermore, the present study highlights a trend towards an inverse correlation between patient age and the methylation status of the GATA-4 promoter region. This potential correlation should however be evaluated in studies with larger patient collectives. Up until now, numerous clinical trials concerning the use of the demethylating drugs AZA and DAC have been able to show promising results in the treatment of AML and MDS patients. This study, in addition to the methylation analysis of hematopoietic cell lines, has reviewed the effect of DAC on the GATA-4, -5 and -6 methylation status of the Raji cell line. For each of the three GATA transcription factors, it was possible to demonstrate a partial demethylation of the promoter region in the Raji hematopoietic cell line. As a consequence, an aberrant methylation of the GATA-4, -5 and-6 promoters could be used as a biomarker for AML diagnosis, prognosis and therapy. An analysis of the mutations of the GATA-4, -5 and-6 transcription factors could contribute to the evaluation of a link between epigenetic and genetic alterations in the pathogenesis of AML.