The purpose of this study was to evaluate the possible relation between dental patient's state anxiety, demographic factors and past experience of treatments with their trait anxiety in patients undergoing root canal treatments (RCT).Materials and Methods: 60 patients participated in this study. A single molar was treated in every patient. At their first visit, patients were asked to fill out a questionnaire about their demographic and educational status as well as a Persian version of STAI-T (Spielberger Trait Anxiety Inventory). At the second visit they filled out a STAI-S (Spielberger State Anxiety Inventory) before going through the dental procedure.Results: Our results showed a significant correlation between state and trait anxiety (P = 0.001). We also found no significant correlation between age and state anxiety (P = 0.932). However, no significant difference was found neither between education and state anxiety (P = 0.78) nor between past RCT experience and state anxiety (P = 0.88). In addition, our analysis indicates no correlation between state anxiety and total number of injections (P = 0.68). According to the patient's answers, the most stressful part of dental procedure was drilling (37%). Conclusions:Our results suggest that there is a relation between trait anxiety and state anxiety. Also, dental procedures are not a source of anxiety in patients with higher trait anxiety per se.