This study aimed to investigate the relationship between managerial narcissism and the readability of financial reporting in companies listed on the Tehran Stock Exchange. In recent years, the attention of accounting and finance researchers to the role of behavioral and psychological characteristics of managers in the quality of financial reporting has increased. In the meantime, managerial narcissism, as one of the important personality traits, can affect the way financial information is disclosed and presented. Narcissistic managers usually tend to present a positive and superior image of their performance and in some cases, they may affect the perception of information users by using complex and ambiguous language in financial reports. Therefore, examining the relationship between managerial narcissism and the readability of financial reporting can help to better understand managerial behaviors in the information disclosure process. The statistical population of the study includes companies listed on the Tehran Stock Exchange, which were selected as a research sample using the systematic elimination method, 145 companies during the period 2018 to 2024. In this study, the readability of financial reporting was measured using the Fogg index as one of the common criteria for measuring the complexity of financial texts. Also, the narcissism of managers was measured using indicators based on managerial behaviors, including the level of capital expenditures and some criteria related to managerial optimism. The multivariate regression method and mixed data were used to test the research hypotheses. The results of data analysis show that there is a significant relationship between the narcissism of managers and the readability of financial reporting, such that an increase in the signs of narcissism in managers is accompanied by a decrease in the readability of financial reports.