The nature of employees' psychological contracts has gained relevance in the last decade due to changes in the employment relationship. However, little research has been conducted in Australia. The present study examined the psychological contracts of 90 MBA students in two Australian universities and the effects of contract violation on indices of organisational behaviour. Survey batteries, consisting of the Psychological Contract Scale, measures of commitment and trust, and of perceptions of contract violation, were administered. Findings indicated that the perception of contract violation was associated with lower organisational commitment and trust. Significantly, it was found that the impact of contract violation on commitment and trust was mediated by relational, but not by transactional, contract scores.