This study examined how leader-member exchange differentiation could affect nurses' perception of organisational justice as well as the moderating effect of task interdependence on this link. Teams are essential to the health-care industry. However, the perception of injustice may lead to a high level of nurse turnover. Data was collected from 187 nurses distributed in eight units in a mid-western hospital in the USA. Hierarchical linear modeling was used to analyze the cross-level interaction of leader-member exchange variability and task interdependence on individual-level perceptions of justice. Leader-member exchange variability was significantly related to distributive justice and interactional justice but not significantly related to procedural justice. The interaction term was significantly related to interpersonal justice, but not to procedural justice or distributive justice. This study showed that if leaders demonstrated a variation in treatment of different subordinates, nurses could perceive this as unfair regarding distribution and interaction; when the group was highly task interdependent, this kind of perception of 'unfairness,' particularly regarding interpersonal treatment, became even more salient. Preferential and inconsistent treatment by them within the work group could introduce nurses' perceptions of unfair treatment. It is of crucial importance to provide training for supervisors on how to display relatively consistent behaviour towards nurses, particularly when the teams are highly task interdependent. © 2012 John Wiley & Sons Ltd.