Following CNS demyelination, adult oligodendrocyte progenitor cells (OPCs) can differentiate into new myelin-forming oligodendrocytes in a regenerative process called remyelination. While remyelination is very efficient in young adults, its efficiency declines progressively with ageing. Here we performed proteomic analysis on OPCs isolated acutely from the brains of neonate, young and aged female rats. Approximately 60% of the proteins are expressed at different levels in OPCs from neonates compared to their adult counterparts. The amount of myelin-associated and cell adhesion proteins are increased with age, while cholesterol-biosynthesis, transcription factors and cell cycle proteins decreased. Our experiments provide the first ageing OPC rodent proteome, revealing the distinct features of neonatal and adult OPCs, and providing new insights into why remyelination efficiency declines with ageing and potential roles for aged OPCs in other neurodegenerative diseases.