Background: The prevalence of symptoms of allergic diseases has increased significantly during the last decades. However, studies into time trends of atopic sensitization among children are limited and have focused on aeroallergen sensitization. We aimed to investigate time trends in the prevalence and degree of atopic sensitization to inhalant and food allergens among children (0-17 years) with symptoms of allergic disease. Methods: Sensitization data of all children tested in our clinical laboratory during 1994-2014 were analyzed. Sensitization was detected using the ImmunoCAP system and defined as a specific IgE level of = 0.35 kU/L. Trends in sensitization rates to 5 food and 5 aeroallergens for different age categories were investigated with logistic regression, adjusted for age and sex. Results: Sensitization data of 18 199 children were analyzed. Between 1994 and 2014, a steady and statistically significant increase in overall sensitization rate was found (from 40.5% in 1994 to 48.9% in 2014, adjusted odds ratio [aOR] 1.01 per year, 95% confidence interval [CI] 1.00 to 1.01, P = .003). This increase in sensitization rate was mainly explained by increasing aeroallergen sensitization among 4- to 11-year-old children (aOR 1.02, 95% CI 1.01 to 1.02, P <.001). We found no increase in sensitization rates to food and aeroallergens in other age categories. The degree of sensitization did not change significantly during the study period (all tests P > .15). Conclusion: We observed a statistically significant increase in sensitization rate between 1994 and 2014 among children with symptoms of allergic disease. This was mainly explained by increasing aeroallergen sensitization among 4-to 11-year-olds.