Objective To explore the effect of olfactory bulb (OB) removal on neurogenesis in subventricular zone (SVZ) by observing the changes of proliferation and differentiation of new cells originated there. Methods An animal model of OB removal was created. Nissl staining and immunohistochemistry for showing the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) and BrdU were done in the brain tissue from adult OB removal rats and observation was made under the light microscope.The total cell number and the number of PSA-NCAM and BrdUpositive cells on the two sides of RMS were counted and analyzed, and the morphological changes of PSA-NCAMpositive cells were observed. Results 1The total cell number and the BrdUpositive cell number on the right side of the RMS in the rats with OB removal increased compared with those on the left side, but the percentage of the BrdUpositive cells decreased apparently with the operation delay after OB removal. 2There were more PSANCAMpositive cells with long processes in the granular layer on the side of OB removal than those on the control side. In addition, some PSA-NCAMpositive cells with long processes were also observed in the RMS at the edge of the excision.Conclusion Young neurons still migrate along the RMS after the OB removal but the prolife