COPSAC is a clinical research unit for paediatric asthma research with the aim of developing evidence-based prevention strategies. COPSAC’s method is prospective clinical birth cohort studies of which two (COPSAC2000 and COPSAC2010) are currently followed at the research unit. Endophenotyping is based on daily diary cards and comprehensive longitudinal objective assessments exploring systems biology and gene-environment interactions in the origin of atopic diseases. COPSAC comprises a multidisciplinary research cluster with competences in pediatrics, pulmonology, allergology, dermatology, microbiology, immunology, genetics and statistics, and participates in national and international research collaborations. Novel findings are communicated through publications in international peer-reviewed journals and textbooks, and through lectures at international scientific meetings. Her Royal Highness Princess Benedikte is Patron for COPSAC.