Rat pheochromocytoma PC12 cells undergo neuronal differentiation in response to nerve growth factor. We show here that exposure of PC12 cells to Nardostachys chinensis glycoside induces the outgrowth of neurites, increases the activity of AChE, triggers cell cycle arrest in G1 and enhances the expression of growth associated protein 43 (GAP-43). Both the outgrowth of neurites and the increase in AChE activity are prevented partly by PD98059, a specific inhibitor of MEK1. These results suggest that N. chinensis glycoside induces the characteristics of neuronal differentiation in PC12 cells via the mitogen-activated protein kinase (MAPK)-related signal cascade.