Mouse nestin, an intermediate filament gene, is transiently expressed during the development of the central nervous system. In order to find the clue of its function during neural development, we tried to find out the gene expression pattern during the neuronal differentiation of P19 EC cells induced RA. RT-PCR showed that nestin was transiently expressed during P19 neuron differentiation, with a peak at day 4 of this process. However, BMP4, a neural precursor cell marker, was transiently expressed with its highest level at day 6, while NF160 kD a terminal differentiated neuronal marker, was increasingly expressed during the whole process. These results implied that nestin might play some roles during the process of neural progenitor cells differentiating into neural precursor cells. Moreover, immunostaining showed that nestin was located in the neurite and the growth cone of the P19 neuron, suggesting that nestin might be also involved in the process of the establishment of neural connection.