Dupilumab is a fully human monoclonal antibody targeting interleukin (IL) 4 and IL13 pathways. We performed a retrospective observational study to evaluate the efficacy of dupilumab for the treatment of adult patients referred to our department, from January 2019 to May 2021, with a diagnosis of moderate to severe atopic dermatitis (AD) and concomitant chronic rhinosinusitis with nasal polyps (CRSwNP), with a clinical indication for dupilumab treatment. Skin disease activity was assessed using EASI, Numerical Rating Scale (NRS) for pruritus (P-NRS) and sleep (S-NRS), and Dermatology Life Quality Index (DLQI). The CRSwNP activity was evaluated using 22-item Sino-Nasal Outcome Test (SNOT-22), endoscopic nasal polyp score (ENPS), nasal congestion or obstruction score (scale 0-3), loss-of-smell score (scale 0-3), and rhinosinusitis disease severity (visual analog scale 0-10 cm). A significant improvement of all the score values was recorded assessing patients at baseline, week (W)16, and W24. In particular, concerning the CRSwNP, a reduction of ENPS score (baseline: