In the diagnosis of otitis media it is easy to be misled by the patient's history, the physical examination, and the usual hearing tests, particularly as regards the presence of fluid in the middle ear. Despite the presence of fluid, the physical findings may not be characteristic and the hearing loss shown in audiograms may range from mild to severe. Decisive information is furnished by the pneumatic otoscope, which reveals limited excursion of the eardrum. The binaural transmission test helps to establish the diagnosis. Treatment aims to restore normal function of the eustachian tube and should include treatment of contributing systemic disease. If the condition is chronic, myringotomy and the use of indwelling plastic tubing is advised.