Chin marking by the European rabbit (Oryctolagus cuniculus) is one of the classic but still little understood examples of mammalian chemical communication. To investigate whether the sexes differ in performance of this behavior, we compared the frequency of spontaneous chinning and chinning in response to the chin marks of conspecifics in 20 intact male and 20 intact female chinchilla-breed rabbits, and in five gonadectomized animals of each sex. Contrary to the expectation of greater chinning activity in males, no significant sex differences were found. Frequencies of spontaneous chinning were similar in the two sexes, large and stable individual differences were observed in both, chinning increased in both when marks from unfamiliar conspecifics were present, and both directed chin marks to objects marked by conspecifics more than to unmarked objects. Individual chinning frequencies correlated positively with urination but not defecation in both sexes, and spontaneous and odor-induced chinning were significantly reduced both in castrated and ovariectomized animals. The findings suggest that chinning is an equally significant part of the communication system of male and female rabbits and that its expression may be regulated by similar olfactory, hormonal, and social mechanisms.