Abstract Cell surface expression of NM23 protein is only observed on tumor cell lines, but not on normal cells. To examine what types of tumor cell line express the cell surface NM23 protein, we measured the cell surface NM23-H1 and NM23-H2 proteins of leukemia line cells on various cellular lineage and differentiation stages. The NM23-H1 was expressed on myeloid leukemia lines but not lymphoid lines, while NM23-H2 was only expressed on erythroleukemia lines. The complement-dependent cytolysis confirmed the expression of these proteins on the surface. Surface NM23-H1 and NM23-H2 proteins were decreased during in vitro erythroid and granulocyte differentiation. These results show that the surface expression of NM23 proteins is related to cellular lineage and differentiation stage of leukemia line cells.