Mate availability has been shown to influence intrasexual competition and mate-guarding behavior across a variety of species. Nevertheless, little is known about how perceived mate scarcity affects such behavior in humans. The purpose of this study was to examine the effects of experimentally induced perceptions of mate availability upon intrasexual competition, jealousy and aggressive mate guarding behavior. Heterosexual undergraduate students (N = 124, 60 women, 64 men) were primed with perceptions of either mate scarcity or mate abundance and subsequently completed measures of intrasexually competitive attitude, jealousy and willingness to aggress against a mate-poacher (either directly or indirectly). For both men and women, results showed that individuals who were exposed to the mate scarcity condition reported significantly more intrasexual competition, jealousy and willingness to aggress indirectly against a matepoacher compared to those exposed to the mate abundance condition. Results provide evidence of an attitudinal and behavioral shift toward sexual conflict when individuals perceive mates to be a scarce resource.