Rapid urbanization over the last hundred years has dramatically altered the natural landscape,the functioning of the ecosystem and biodiversity,which have many negative consequences,including the emergence and re-emergence of infectious diseases originating from wildlife.Most of the studies of urbanized wildlife have focused on monitoring the population size and the diversity of different species.Lacking is knowledge of how urbanization affects wildlife health status and reservoir-competence.In order to better understand these consequences,we live-trapped brown rats (Rattus norvegicus) in urban (n=7) and rural (n=12) areas in Henan Province,China during September and October,2013.We found that 1) the urban rats were relatively bigger (body length and body mass) compared to their rural counterparts,although rural rats had longer tails and bigger ears than urban rats; 2) the absolute and relative spleen mass and the number of total leukocytes of urban rats were relatively higher compared to their rural counterparts.Based on our preliminary results,we suggest that urban rats invest more in their cell-mediated immunity.However,increasing the sample size and more comprehensive investigations (functional immune and stress measurements,parasite burdens) are needed to clarify the underlying causes.