Personality has been identified as an influential variable associated with irrational beliefs. However, only a few studies have examined its prediction on irrationality. This study was conducted to develop a better understanding of how specific personality traits (openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism) serve as predictors of irrational beliefs in Malaysian teachers. A Big Five Inventory (BFI) and Teacher Irrational Beliefs (TIB) were employed to evaluate 132 primary school teachers from 16 government-funded schools in the district of Muar, Malaysia. In general, the correlation results showed that all the personality traits examined significantly correlated with irrational beliefs. The multiple regression results indicated that openness to experience and extraversion had a significantly negative influence on the irrational beliefs of the teachers while neuroticism showed not only a significant positive influence on the teachers' irrational beliefs but it was also found to be a strong predictor of their irrationality. The findings highlight the importance to take personality traits into account as potential vulnerability factors of irrational beliefs.