The transcription factor AML1 (CBFA2) is indispensable for early fetal hematopoiesis, but also transactivates target genes which are important for further downstream hematopoiesis. However, little is known about the impact of AML1 on lineage-committed stages. We investigated the transcription of AML1 in subfractions of four normal adult bone marrow aspirates isolated by fluorescence-activated cell sorting. AML1 is transcribed in early (CD34+/CD38-) and late (CD34+/CD38+) hematopoietic progenitors, B-cell precursors (CD10+/CD19+) as well as in immature monocytes (CD14-/CD11c+), myeloid (CD15+/CD33+ and CD15+/CD33-) and erythroid (GPA+/CD3-/CD45-) cells, but not in T lymphocytes (GPA-/CD3+/CD45+). These data suggest that in adult hematopoiesis AML1 may be critically involved in differentiation of early hematopoietic progenitors, erythroid cells, and lymphoid precursors. These subfractions are interesting targets to study the importance of AML1 in definitive hematopoiesis.