Objective Investigated the expression of NB-3 in the mouse during the development of the central nervous system. Methods We utilized the heterozygote of NB-3 transgenic mouse which labeled by the EM>Lac Z/EM> gene. X-gal staining was used to detect the expression and location of NB-3 in brain of E12, E14, E16, E18, P0, P7, P14 and adult mice. Results 1. NB-3 was detected first in the E14 during embryonic development. Then it was also detected in the surrounding lateral cerebral ventricle, cortex, thalamus, hypothalamus and hippocampus. It mainly focused on the region of the Ⅱ/Ⅲ, Ⅴ layers of the cortex. 2. Early in the postnatal period in the cerebrum, the expression of NB-3 increased abruptly to a high level, reaching maximum at the postnatal seventh day. Thereafter, the expression declined a little, and it maintained during adulthood. 3. The distribution of NB-3 was widespread in the cerebrum of adult mouse. The strongest expression was detected in the layers Ⅱ/Ⅲ and Ⅴ, the piriform cortex, the amygdala, the thalamus, the hypothalamus and CA1 of the hippocampus etc. Conclusion NB-3 is widely expressed not only in the embryonic period but also in the adulthood although the expression intensity is different. These results suggest that NB-3 may pl