Objectives: The aim of the study was to systemically investigate the risk of subsequent irritable bowel syndrome (IBS) in children with antecedent allergic diseases in a population-based case-control study in Taiwan. Methods: We evaluated 11,242 children (age range: 7-18 years) with IBS and 44,968 age- and sex-matched control subjects who had been examined between 2000 and 2008. IBS odds ratios were calculated for children with antecedent allergic diseases, including allergic conjunctivitis, allergic rhinitis, asthma, atopic dermatitis, urticaria, and food allergy. Results: Children with antecedent allergic diseases had a greater risk of IBS than did control subjects (P < 0.001). Among the 6 evaluated diseases, the highest adjusted odds ratio of 1.78 was observed with allergic rhinitis (95% confidence interval [CI] 1.69-1.87). With 2 or more allergic diseases, the adjusted odds ratios increased to 2.06 (95% CI, 1.93-2.19) for all subjects, 2.07 (95% CI, 1.88-2.28) for girls, and 2.18 (95% CI, 2.02-2.35) for children 12 years or older. Conclusions: Preschoolers with a history of allergic disease had an increased risk of subsequent IBS development upon reaching school age. This risk increased in the presence of concurrent allergic disease and a higher clinical allergy burden.