In the current study, the ability of ATP to promote apoptosis in myeloblasts at different ages was investigated. We have observed that high concentration of extracellular ATP (>1 mM), which activates P2X7 receptor, produced cell shrinkage an increase in the number of events in the sub-G0/G1 region of the cellular cycle and annexin-V/propidium iodide label, which characterizes the apoptotic cell death. In addition, BzATP produced apoptosis, but not ADP and UTP. Gr-1+ cells express the P2X7 receptor and oxidized ATP, a specific P2X7 inhibitor, blocked the ATP-dependent apoptosis. ATP-dependent apoptosis is decreased by aging in myeloblasts of 12 and 22-month-old mice. Furthermore, P2X7 expression decrease was observed in older mice, explaining apoptosis decrease. This decrease in apoptosis by aging may be related to some diseases in the myelocyte lineage. © 2007.