Up to 80 % of children can develop otitis media with effusion (OME) between birth and school age. Responsible are longstanding impairments of tubal ventilation which are based primarily on mechanical or functional obstructions. A quarter of the subjects affected by OME show either recurrent episodes over 3 months or protracted clinical courses and in these children an extended diagnosis is required. Besides infection-related adenoid hypertrophy, the differential diagnosis should include ciliary dysfunction, chronic rhinosinusitis, craniofacial malformations, gastroesophageal reflux, tumors and cancer treatment in the nasopharynx and in particular allergies. Clinical and experimental studies have indicated that respiratory allergies promote both adenotonsillar hypertrophy as well as inflammatory alterations in the mucous membranes of the Eustachian tube and middle ear and can thus promote the formation and persistence of OME. Because of a sensitization rate of about 30% in the general population at the predilection age from 3-6 years (KiGGS study), standard diagnosis (e.g. otoscopy and audiometry) should be extended by allergy diagnostic testing, especially in cases of recurrent or prolonged courses of OME. The most common classes of medications used for childhood allergies are antihistamines and nasal steroids, which could optimize the standard treatment of OME.