An expanded bed system has been developed for a novel application in which the separation and enrichment of neural stem cells from a sample containing a mixture of stem and progenitor cells is achieved based on the difference in the sizes of the aggregates of these types of cells. Inert Sephadex beads and flocculated yeast cells were used as experimental controls and references. The characteristics of the separation of neural stem cell aggregates based on size are similar to those achieved with flocculated yeast where cell-to-cell aggregation controls the pattern of size separation different from those of inert Sephadex beads.