The present study aims at measuring the effect of a relaxation-based training programme on reducing the level of suspicious thinking among warned students at Al-Balqa Applied University. To achieve the objectives of the study, a relaxation-based training programme was prepared and the Kurmash Scale was used to measure the students' level of suspicious thinking. The results indicated that the training programme had an effect on reducing the students' level of suspicious thinking, and there were statistical differences attributed to the gender variable, in favour of females, and the faculty variable, in favour of humanities faculties. This study recommends holding a series of seminars and lectures that aim at raising students' awareness about the adverse effects of suspicious thinking and how to overcome it. The significance of this study lies in identifying the important role of relaxation in reducing the level of suspicious thinking among university students, at both the academic or behavioural levels.