Because of its anatomic and functional connections, middle ear disorders frequently occur in sinusitis. Its prevalence, however, is likely to be underestimated. We evaluated the prevalence of Eustachian tube dysfunction in children with chronic sinusitis, in a large group of patients with chronic respiratory symptoms and its possible relationship with respiratory allergy. From a population of 1810 children with respiratory symptoms referred to our Pediatric Allergy Center, subjects with chronic sinusitis diagnosed by clinical criteria were selected. The children underwent testing of Eustachian tube function by tympanometry and of allergy by skin tests with common environmental allergens. Patients were divided into three groups according to age: group 1, <3 yr; group 2, between 3 and 6 yr, group 3, older than 6 yr. Overall 402 children (22.2%) had clinical diagnosis of chronic sinusitis according to the established criteria. Thirty-three patients were in group 1, 299 in group 2, and 70 in group 3. Altered middle ear pressure was found in 69.1% of patients, with a significantly higher rate of altered tympanograms in younger children (p = 0.001). A positive skin-prick test was found in 29.8% of children, with a significantly higher rate of positivity in older children (p = 0.015). The decrease in the rate of Eustachian tube dysfunction with age is likely to be associated with the anatomic development of the upper airways, while the presence of atopy does not seem to play a role in their occurrence.