Addressing the lack of research and knowledge about organizational silence in the nascent but promising Iranian startup ecosystem, this study examines the relationship between personality factors and organizational silence in Iranian startups. Data were collected using Vakola and Bouradas Organizational Silence Questionnaire and NEO Personality Inventory filled by 532 startup employees in Iran, then analyzed by Pearson and multivariate regression tests. Hypotheses were tested through SPSS. Data analysis demonstrated that personality factors predict 17.0% of the variance of organizational silence, and there is a significant relationship between each personality factor with organizational silence in startups. The strongest and weakest correlations with organizational silence were observed for openness to experiences and conscientiousness, respectively. The study is cross-sectional, so its results cannot be casually inferred; longitudinal studies are needed to obtain more comprehensive information. Access to qualified respondents was challenging because of startup managers’ overall conservativeness spirit and tendency to withhold information about their employees. This study has implications for startup managers and decision-makers. Since it has examined a destructive organizational phenomenon in the specific context of startups, this knowledge will help managers recognize and resolve organizational silence. This study has filled the research gap by examining the organizational silence in Iranian startups for the first time and has implications for theoretical development in this novel context; furthermore, it helps startup managers to deal with organizational silence more effectively.