In this study male and female rats were exposed to mildly aversive stimuli, namely, an open-field and 5, 90-dB noise bursts. The rats were exposed alone and in pairs. When pairs were used, some of the partners were pre-treated to exhibit calm or alarmed behaviour during noise-burst trials. This test was conducted to assess whether freezing behaviour by the target rat was reduced or enhanced by the presence and/or behaviour of a companion. Results indicated a marked sex difference, males freeze more than females. No companion influence was found for male rats. In contrast, female rats increased freezing duration when accompanied by an alarmed partner as opposed to a naYve one. The results suggest that female rats habituate rapidly to the environment, more so than males, and thus enhance the likelihood of attending to the behaviour of the companion.