This record contains raw data related to article “Prevalence of familial link in patients affected by chronic rhinosinusitis with nasal polyposis" Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory condition substantially impacting patients’ quality of life, typically associated with type inflammation and frequent comorbidities like asthma, and/or nonsteroidal anti-inflammatory drug exacerbated respiratory disease (N-ERD). So far, there is minimal awareness and understanding of possible genetic factors associated with CRSwNP, apart from patients with a clear genetic disorder such as cystic fibrosis. The aims of this study were to assess the prevalence of familial link in a large cohort of patients affected by CRSwNP and to evaluate whether it was associated with specific phenotypes.