Exposure to domestic violence in childhood has serious consequences for children’s health and well-being and is an important predictor of domestic abuse. However, as compared to other forms of domestic abuse, the effects of exposure to domestic violence on the quality of sibling interactions have been relatively underexplored. The major objective of the current study was to examine the impact of exposure to domestic violence on the quality of the sibling relationship, and to better understand the influence of age and gender on sibling aggression. Social learning theory and family systems theory were the guiding frameworks for this study. Participants consisted of 47 school-aged sibling dyads with a history of exposure to domestic violence recruited from the community. Aggressive behaviour was measured by standardized questionnaires completed by mothers and children and by observations of naturalistic sibling interactions. As predicted, analyses of observed aggression which controlled for exposure to domestic violence revealed brothers were significantly more aggressive than sisters or mixed gender dyads. Unexpectedly, analyses of observed aggression found that boys were significantly more aggressive with their siblings than their female counterparts when exposure to maternal violence was taken into account. Findings indicate that children exposed to domestic violence, especially boys, may be at greater risk for aggressive behaviour. Results are expected to be useful for practice and future research.