Background & Aim: One of the main components of social cognition is the theory of mind (TOM), which refers extensively to the ability to understand emotions, motivations, thoughts and subsequent perceptions of others' behaviors. Therefore, the aim of this study was to determine the relationship between signs of paranoid, schizoid and schizotypal personality disorders, with defect of the theory of mind. Methods: In this descriptive-correlational study, 210 students of Tabriz University were selected by cluster random sampling. Then, students completed the Millon III Multidimensional Clinical Questionnaire and the Mind Reading Test through the Baron-Cohen Eye. Data were analyzed using structural equation modeling (SEM) by means of Lisrel-8. 85 software. Results: The findings of the study showed that the signs of paranoid and schizotypal personality, with respective coefficient of explanation (0. 47 and 0. 51) and t (5. 82 and 5. 97), were able to positively explain 47% and 51% of changes in the theory of mind defects, respectively, (P<0. 05). While the symptoms of schizoid personality with a coefficient of explanation (0. 11) and t (1. 20) had no significant role in explaining the changes in the theory of mind defect. Thus, there was no significant relationship between the symptoms of schizoid personality and the defect of the theory of mind. Conclusion: The findings suggest that signs of paranoid and schizotypal personality disorders can be predictors of the theory of mind defect. On the other hand, symptoms of schizoid personality disorder were not capable of predicting the theory of mind defect.