In this study, we investigated the relationships between psychological contract breach, affective commitment, and two types of employee performance (i.e. civic virtue behaviour and in-role performance). It was predicted that an experience of contract breach can severely hurt the affective commitment of the employees and this, in turn, results in poor in-role performance and less civic virtue behaviours. Results revealed that affective commitment had differential mediating effects on the two types of employee performance. That is, affective commitment mediated the relationship between breach and self-reported and supervisor-rated civic virtue, but not the relationship between breach and in-role performance.