Transcriptional dysregulation is associated with haematological malignancy. Although mutations of the key haematopoietic transcription factor PU. 1 are rare in human acute myeloid leukaemia (AML), they are common in murine models of radiation-induced AML, and PU. 1 downregulation and/or dysfunction has been described in human AML patients carrying the fusion oncogenes RUNX1-ETO and PML-RARA. To study the transcriptional programmes associated with compromised PU. 1 activity, we adapted a Pu. 1-mutated murine AML cell line with an inducible wild-type PU. 1. PU. 1 induction caused transition from leukaemia phenotype to monocytic differentiation. Global binding maps for PU. 1, CEBPA and the histone mark H3K27Ac with and without PU. 1 induction showed that mutant PU. 1 retains DNA-binding ability, but the induction of wild-type protein dramatically increases both the number and the height of PU. 1-binding peaks. Correlating chromatin immunoprecipitation (ChIP) Seq with gene expression data, we found that PU. 1 recruitment coupled with increased histone acetylation induces gene expression and activates a monocyte/macrophage transcriptional programme. PU. 1 induction also caused the reorganisation of a subgroup of CEBPA binding peaks. Finally, we show that the PU. 1 target gene set defined in our model allows the stratification of primary human AML samples, shedding light on both known and novel AML subtypes that may be driven by PU. 1 dysfunction.