Background <p>The aim of this study is to investigate the association between preoperative anxiety and postoperative pain after endodontic treatment in vital symptomatic mandibular molar teeth.</p> Methods <p>132 patients who came for endodontic treatment of symptomatic molars were asked to complete the ‘Modified Dental Anxiety Scale’ (MDAS) to assess preoperative anxiety. After the treatment, patients were provided with a pain assessment form and requested to record average daily pain intensity for seven days. Postoperative pain was assessed using a Visual Analog Scale (VAS). The completed forms were collected one week later. Data were analyzed using Mann-Whitney-U test, Chi-square test, one-way ANOVA, Kruskal-Wallis and multivariable linear regression analysis tests. The significance level was set at <i>p</i> &lt; 0.05.</p> Results <p>Analysis of postoperative pain values revealed a significant difference between groups in the first 3 days postoperatively (<i>p</i> &lt; 0.05). Post-hoc pairwise comparisons performed for the first three postoperative days demonstrated a statistically significant difference in pain reduction, particularly between the moderate and high anxiety groups (<i>p</i> &lt; 0.05). Regarding the relationship between sex and postoperative pain, a significant difference was found only on postoperative day 3 (<i>p</i>= 0.031). A statistically significant difference was observed among the groups regarding postoperative analgesic use (<i>p</i> &lt; 0.001). Multivariable regression analysis indicated that anxiety was associated with postoperative pain after adjusting for potential confounders (<i>p</i> = 0.018).</p> Conclusion <p>In conclusion dental anxiety may influence postoperative pain. Patients with higher dental anxiety tend to experience greater postoperative pain. Evaluating patients’ anxiety levels can contribute to more effective management of the treatment, and the implementation of anxiety-reducing strategies may help to lower the risk of postoperative pain.</p>