In acute myeloid leukemia (AML), many of the remaining normal-appearing cells exhibit various abnormalities. An interpretation is that these cells are descendants of leukemic cells which have succeeded in overcoming the major final differentiation block that exists in AML. Direct evidence is quoted that red cell precursors in AML are of leukemic descent and it is claimed that the target cell of AML is the pluripotent stem cell. Next, evidence has been compiled that all three cell lines (red cell, n. granulocytes, platelets) exhibit qualitative defects in "prelukemia." Hence it is postulated that preleukemia per se doses not exist but that preleukemic states which with a rather high frequency sooner or later end in overt AML are actually true leukemias that, however, differentiate reasonably well. Another way of phrasing it is that preleukemic states are AMLs that present in partial and sometimes long-lasting remission, which only after months to years lose their differentiation ability and then are classified as AML.