This study was undertaken to assess sex differences in the vicarious learning magnitude by exploiting an aversive paradigm in adult mice. Mouse observers were individually subjected to an observational compartment next to the training compartment wherein three demonstrators received 1)a daily 30-min presentation of vanilla odors for 3 consecutive days; or 2)3-days of 30-min vanilla odors contingent on the delivery of 15 pseudo-randomly-arranged footshocks (0.5 mA, 2 s in duration per shock). Vanilla odors-induced freezing response (FR) was used to indicate observers’ vicarious learning magnitude. Approximately 24 hours after the conclusion of learning regimen, presentation of vanilla odors was found to enhance observers’ FR comparably in both male and female mice. To assess the roles of corticosterone (CORT) in learning, consolidation, and retrieval stages, systematic injection of metyrapone (50 mg/kg) was used to inhibit CORT synthesis prior to learning, immediately after the learning and prior to retrieval. We noticed not only observation-stimulated CORT but also memory retrieval-induced CORT secretion affected FR magnitudes regardless of sexes. Moreover, presentation of conditioned auditory stimulus (acoustic sound from demonstrators receiving odors and footshocks in combination) resulted in greater FR magnitude in male mice but no such changes in female mice. To conclude, 1) observation-stimulated CORT secretion and memory retrieval-induced CORT secretion are necessary for performing such vicarious fear conditioning in observer mice, albeit no sex differences; 2) mouse demonstrators’ auditory cues seem to be as important as olfactory cues in facilitating such vicarious fear learning in male, but not in female, mouse observers.