Previous research has documented sex differences in nonverbal communication. What has remained unknown is whether similar sex differences would exist with regard to olfactory communication via chemosignals, a relatively neglected nonverbal communication medium. Because women generally have a better sense of smell and greater sensitivity to emotional signals, we hypothesized that compared with male participants and relative to a neutral control condition, female participants would emulate the fearful state of the sender producing the chemosignals. Facial electromyography was used in a double-blind experiment to measure in the receiver a partial reproduction of the state of the sender, controlling for the moderating influence of the sex of the sender and receiver. The results indicated that only female participants emulated the fearful state of the sender. The present study revealed a boundary condition for effective chemosignaling by reporting behavioral evidence of sexual asymmetry in olfactory communication via chemosignals.