AIM: To study the protocol and condition that induce bone marrow stromal cells (MSCs) to differentiate into neuron in vitro by baicalin, a kind of flavonoid isolated from an important medicinal plant Scutellariae Radix . METHODS: MSCs from adult rats were induced by baicalin in serum-free medium for 6 h, and postinduced for 6 d. The morphological changes of MSCs were evaluated by light microscope. The positive percentages of neuron-specific enolase (NSE), 200-kilodalton neurofilament (NF), glial fibrillary acidic protein (GFAP) and vimentin expression were measured by immunocytochemistry with ABC staining. Hoechst 33258 staining was used to measure the cell viability by fluorescence microscope. RESULTS: After induction for 6 d, MSCs displayed neuronal morphologies, such as pyramidal cell bodies and processes formed extensive networks. The positive percentages of NSE, NF, GFAP and vimentin protein expression were 70.5%?11.6%, 68.3%?13.4% ,