In most mammals, the olfactory system is crucial in the processing of odor information related to mate recognition. In mice two regions of the olfactory bulb (OB), the main olfactory bulb (MOB) and the accessory olfactory bulb (AOB), have been shown to play a complementary role in the processing of odor information associated to mate recognition. Furthermore, the OB is among the few regions in the brain that exhibits adult neurogenesis, which has been extensively characterized in the MOB. Adult neurogenesis varies under different physiological conditions including exposure to conspecifics odors. Newly born cells originate in the subventricular zone from progenitor cells, and migrate to the OB where they mature into inhibitory neurons, the granular and periglomerular cells, and are functionally integrated into the existing neuronal network. Little is known, about the role and extent of adult neurogenesis in the AOB and whether it can be regulated by behavior. Here, using immunohistochemical techniques and BrdU to label newly born cells, we determined the extent of adult neurogenesis in the mice AOB. We found abundant labeled cells in the granule cell layer (GCL) (4,191±564 and 2,759±573 BrdU+cells/mm3, male and female mice respectively) with no significant differences between genders. The majority of the BrdU+cells corresponded to neurons (93%), as determined by double labeling with NeuN, a marker of mature neurons. Moreover, we exposed sexually naive adult females to soil bedding odorized by a male and quantified newly born cells. We found that neurogenesis was significantly increased in the GCL of the posterior AOB in odor-exposed females (2480±226 v/s 1275±495 BrdU+cells/mm3; p<0.01). These results indicate that the AOB exhibits considerable neurogenesis, which shows differences in the anterior and posterior axis. Our results also indicate that neurogenesis in female mice may be regulated by exposure to male odors, suggesting a possible role in mate recognition.