AML1-ETO (Acute Myeloid Leukemia 1-Eight Twenty One) caused by the translocation t(8;21)(q22;q22) is a mutated transcription factor contributing to AML development. Although associated with a favorable prognosis, half of the patients fail to achieve long-term survival. We examined the role of the transcription factor Growth factor independence 1 (GFI1) in the initiation and progression of leukemia and exploited the use of a drug targeting GFI1 expression in the context of AML1-ETO associated AML. We could show that GFI1 is required for maintenance of AML1-ETO associated leukemia and that loss of GFI1 or targeting GFI1 expression impedes leukemia initiation and progression and could be a potential new therapeutic strategy for patients failing to respond to chemotherapy. Overall design: ChIP-seq profiling of GFI1 in human Kasumi-1 cells and of AML1-ETO in Gfi1 wt and KO mouse spleen cells