Adult female Mongolian gerbils (Meriones unguiculatus) are preferentially attracted to saliva from adult nonsibling males when paired with saliva from male siblings. The focus of the present study was to evaluate the potential role of saliva in the formation of reproductive units. In Experiment 1, olfactory-directed investigations and mate choices of estrous females housed with their brothers and unrelated males were examined. Females sniffed unrelated males more frequently than siblings and were more interested in sniffing the mouth area than other body areas. Importantly, they also solicited and mated exclusively with unrelated males. The purpose of Experiment 2 was to ascertain the origin of the behaviorally active components of saliva by transecting the parotid salivary duct (PDT). When either sibling saliva or water was paired with saliva from a nonsibling PDT male, females did not show the typical preference for saliva from nonsiblings. When social preferences were examined in Experiment 3, virtually all females preferred intact nonsibling males to either PDT nonsibling males or siblings. Results from this study support the hypothesis that saliva is an important oral cue used by females in the selection of sociosexual partners. Furthermore, the parotid gland appears to be a significant source of salivary chemosignals.