A cohort of 946 children who were screened for otitis media with effusion (OME) by serial tympanometry from the age of 2 to 4 years was followed up by otomicroscopy at 7.5 to 8 years of age. At school age, signs of active middle ear disease were present in 2.2% of ears that had been free from OME at preschool age, whereas 12.7% of ears that had suffered from persistent OME and 17.8% of ears that had been treated by a ventilation tube showed signs of active middle ear disease. Otopathologic sequelae (atrophy, tympanosclerosis, atelectasis, and attic retraction) were present in 13.7%, 39.8%, and 87.3% of these ears, respectively. A duration-response effect was found in the association between preschool OME and these sequelae at school age. The high prevalence of otoscopic abnormalities found in this population calls for further follow-up and evaluation of their functional implications.