A human megakaryocyte cell line (B1647) has been established from bone marrow cells obtained from a patient with acute myelogenous leukaemia (FAB M2). The cells were CD34−, CD33+, HLA‐DR+, CD38+, and expressed the immunophenotypic markers of the megakaryocyte lineage (CD41 and von Willebrand factor). Moreover the cells expressed the c‐mpl (thrombopoietin receptor) mRNA and protein. On the other hand, the B1647 cells also possessed erythroid lineage characteristics: the vast majority of cells were glycophorin positive, and about 10% of unstimulated cells stained with an anti‐globin γ chain MoAb. In addition, S1 protection analysis demonstrated expression of β‐globin mRNA, and Epo receptor (Epo‐R) protein was detected by cytofluorimetric assay. Several growth factors, when tested alone or in combination, failed to influence the B1647 cell growth. A significant increase of cell proliferation was observed only after the addition, in serum‐free culture, of recombinant human megakaryocyte growth development factor (MGDF), a recombinant c‐mpl ligand encompassing the receptor‐binding domain and identical to thrombopoietin (TPO), at concentrations ranging from 0.01 to 1 ng/ml. Interestingly, MGDF failed to induce megakaryocytic differentiation of the B1647 cells, but significantly increased the synthesis of the globin γ‐chain.B1647 cells could be a useful model for studying the biological effect of TPO on common megakaryocyte and erythroid progenitors.