Background and Objectives: Chronic rhinosinusitis with nasal polyposis (CRSwNP) is one phenotype of the diffuse type. In spite of surgical and medical treatment, the polyp recurrence rate is high. Recently biologics are concerned as a therapeutic option of it. To figure out adverse events associated with the dupilumab injection in adult patients with CRSwNP.Subjects and Method Retrospective chart review of patients that were treated with dupilumab from January 2022 to December 2022 for CRSwNP was performed. Results: Of 40 patients (23 of male and 17 of female), 8 patients (20.0%) experienced 9 patients (22.5%) adverse events. The most common adverse event was skin reaction (3 patients, 7.5%), followed by 2 of pruritis, 2 of epistaxis. Three patients quit dupilumab after the adverse events, 4 patients continued, and 1 patient hold the next injection. Conclusion Dupilumab is reported to be relatively safe medication. However, physician should notice that adverse events including skin rash can occur after dupilumab injection.