Adenosine 5'-triphosphate (ATP) is implicated in intercellular communication as a neurotransmitter in the peripheral nervous system. In addition, ATP is known as lysosomal exocytosis activator. In this study, we investigated the role of extracellular ATP on demyelination during Wallerian degeneration (WD) using ex vivo and in vivo nerve degeneration models. We found that extracellular ATP inhibited myelin fragmentation and axonal degradation during WD. Furthermore, metformin and chlorpromazine, lysosomal exocytosis antagonists blocked the effect of ATP on the inhibition of demyelination. Thus, these findings indicate that ATP-induced-lysosomal exocytosis may be involved in demyelination during WD.