The models of acute erythroleukemia caused in mice by the Friend retrovirus SFFV (spleen focus forming virus) and the Spi-1/PU.1 transgenesis provide considerable information to help to understand the molecular mechanisms underlying the multi-stage nature of leukemia. Leukemogenesis in these murine models is initiated from an acute hyperplasia of erythroid progenitor cells followed later on by a blastic crisis. This review highlights recent findings demonstrating the key roles of the co-operation of two mutations occurring during leukemic progression, a mutation interfering with differentiation and a mutation conferring a proliferative advantage to cells. Through their multi-step evolution, these mouse erythroleukemia models resemble the two phases of human acute myeloid leukemia (AML). The findings we discuss provide evidence for similar molecular mechanisms involved in the evolution of leukemia in mice and men.