Most kinds of acute otitis media are caused by bacteria transported from the nasopharynx to the middle ear through the eustachian tube. In this investigation the middle ear pressure after Toynbee 's maneuver--swallowing against occluded nostrils--has been registered. Two percent of normal individuals without middle ear disease developed a positive middle ear pressure, while 56 percent of patients with middle ear disease got a positive middle ear pressure. We suggest that the positive pressure created in the nasopharynx at the time of Toynbee 's maneuver is a factor in middle ear disease.