Organizational citizenship behaviour represents the behaviour of the employees that goes beyond their duties. This type of behaviour from the perspective of employer is very desirable since it produces many positive consequences regarding individual and the overall organizational performances. However, readiness of the employees to exert this type of behaviour is influenced by many factors. One of the most important is fulfilment of employees’ psychological contract. Since that there are two basic forms of contracts, relational and transactional, the aim of this paper is to investigate the relationship between these types of psychological contract and organizational citizenship behaviour. For the purpose of testing proposed hypothesis, t-test, Pearson correlation and multiple linear regression analysis were applied. The results showed that there is a positive relation and positive impact of relational psychological contract on the organizational citizenship behaviour, which was not the case when it was about the transactional contract.