The present study investigated expression of α-synuclein (α-syn), a presynaptic protein involved in the pathogenesis of Parkinson’s disease, in erythroid cells. Using various immunological procedures, immunoreactivity of α-syn was unambiguously demonstrated in erythroid lineage in murine bone marrows and peripheral erythrocytes. Expression of α-syn mRNA was also confirmed by in situ hybridization. Furthermore, flow cytometry analysis revealed that approximately 80% of erythroid cells in murine bone marrows expressed α-syn, while more than 90% of peripheral erythrocytes expressed α-syn. Nonetheless, α-syn null mice exhibited apparently no phenotypic changes in erythroid cells as was the case in their brains, suggesting that there might be underlying some redundant mechanisms. Together with previous reports showing the expression of α-syn in lymphocytes and platelets, the present finding supports a contention that α-syn might play some important functions in hematopoietic system.