Gerbils are social rodents which form stable male-female pairs. These pair bonds appear to be based on prolonged association rather than an exclusive mating relationship. However, both sexes contribute to territorial defense and pup rearing. Therefore, pair-bond disruption may be expected to have consequences for subsequent behaviour. This hypothesis was examined in a series of laboratory studies. Behavioural consequences of pair-bond disruption were seen in both sexes and the optimum housing parameters were found to be to pair males and females for 5 weeks and to examine their behaviour 1 week after pair-bond disruption. Two further studies using these parameters were conducted to examine the combined influence of pair-bond disruption and the sex of the animal being interacted with. Results across all studies revealed a consistent pattern. Females showed increased immobility in contact, that is, freezing upon another animal's approach, and altered cage-orientated behaviour, regardless of the sex of the animal they were interacting with. In contrast, males showed decreased social investigation and offense and initiated fewer social interactions. However, these effects were only seen in interactions with other males. No changes in social behaviour were evident in interactions between pair-bond-disrupted males and females. The behavioural strategies of pair-bond-disrupted males and females in a social situation therefore differ. From these studies, it may be concluded that pair-bond disruption has consistent and reproducible effects on subsequent social behaviour in gerbils and that there are important sex differences in the behavioural expression of this.