Abstract： We have previously established a culture method to isolate and cultivate neural stem cells (NSCs) derived from the rat embryonic brain and spinal cord. In the present study, we demonstrate that the spinal cord-derived NSCs can be induced to differentiate into oligodendrocyte precursor cells (OPCs) with a combined treatment composed of (1) conditioned medium collected from B 104neuroblastoma cells (B104CM) and (2) basic fibroblast growth factor (bFGF, 10 ng/ml). After induction, over 95% of the cells displayed bipolar or tri-polar morphology and expressed A2B5 and platelet derived growth factor receptor-α (PDGFR-α), markers that are specific for OPCs. Among PDGFR-α positive OPCs, only a few cells expressed glia fibrillary acidic protein (GFAP) and none expressed β-tubulin Ⅲ. In the presence of B 104CM and bFGF, OPCs proliferated rapidly, formed spheres, expanded for multiple passages, and maintained their phenotypic properties. Upon withdrawal of B 104CM and bFGF, these cells differentiated into either O4/GlaC-positive oligodendrocytes (OLs) or GFAP- and A2B5-positive type-2 astrocytes. Our results indicate that NSCs can be induced to differentiate into OPCs that possess properties of self-renewal and differentiation into oligodendrocytes and type-2astrocytes, a property similar to that of O-2A progenitor cells. The OPCs can be maintained in an undifferentiated state over multiple divisions as long as both B 104CM and bFGF are present in the medium. Thus, large quantity of OPCs can be obtained through this method for potential therapeutical interventions for various neurological degenerative diseases.