This study examined the role of teachers' personal characteristics and mental health status on their frequency ratings of student problem behaviour. A sample of 121 primary school teachers were asked to rate the frequency of a student's behavioural problems, and to self-report their personality traits, psychopathology symptoms and burnout. Overall, the results revealed that teachers' ratings were significantly predicted by their psychopathology symptoms and to a lesser extent by their personality traits and burnout levels. Student and teacher demographic characteristics were also predictive of teacher ratings. Since teachers are among the primary informants of students' mental health, the results of this study pose the need to take into consideration teachers' individual characteristics, when their ratings are critically evaluated during a student's referral process.