||BACKGROUND AND OBJECTIVES: Many children are treated for recurrent acute otitis media and middle ear effusion with ventilation tubes (VT). The objectives are to describe the incidence of VT in Denmark during 1997-2011 from national register data, furthermore, to analyze the determinants for VT in the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010) birth cohort. METHODS: The incidence of VT in all children under 16 years from 1997-2011 were calculated in the Danish national registries. Determinants of VT were studied in the COPSAC2010 birth cohort of 700 children. RESULTS: Nationwide the prevalence of VT was 24% in children aged 0 to 3 three years, with a significant increase over the study period. For all children 0-15 years, the incidence of VT was 35/1,000. In the VT population, 57% was male and 43% females. In the COPSAC2010 birth cohort, the prevalence of VT during the first 3 years of life was 29%. Determinants of VT were: maternal history of middle ear disease; aHR 2.07, 95% CI [1.45-2.96] and siblings history of middle ear disease; aHR 3.02, [2.11-4.32]. Paternal history of middle ear disease, presence of older siblings in the home and diagnosis of persistent wheeze were significant in the univariate analysis but the association did not persist after adjustment. CONCLUSION: The incidence of VT is still increasing in the youngest age group in Denmark, demonstrating the highest incidence recorded in the world. Family history of middle ear disease and older siblings are the main determinants for VT.