In this study,we conducted a series of behavioral and physiological tests to examine the role of the vomeronasal organ in social odor recognition,social interaction,and fitness in golden hamster (Mesocricetus auratus) .We found that male hamsters with vomeronasal organ lesions showed no preference between a predator odor (the anal gland secretion of the Siberian weasels Mustela sibirica) and putative female pheromone components (myristic acid and palmitic acid) ,but were still able to discriminate between these two kinds of odors.In behavioral tests of anxiety,we found that vomeronasal organ removal causes female hamsters to spend much less time in the center and cross fewer center grids of an open field,and males make fewer crossings between light and dark boxes than sham-operated controls.This indicates chronic vomeronasal organ lesion induced anxiety responses in females.In aggressive behavioral tests,we found that chronic vomeronasal organ lesions decreased agonistic behavior in female hamsters but not in males.Pup growth and litter size was not different between groups.Together,our data suggested that vomeronasal organ ablation disrupted the olfactory recognition of social chemosignals in males,and induced anxiety-like and aggressive behavioural changes in females.However,vomeronasal organ lesions did not affect the reproductive capacity and fitness of hamsters.Our studies may have important implications concerning the role of vomeronasal organ in golden hamsters and also in rodents.