Pathologic relation between atelectatic ears and their nasopharynx were investigated in 50 patients with various degrees of atelectatic ears by transnasal fibrescope and C.T. And their morbid adenoids were compared with the adenoids of 20 patients with mouth breathing but free from ear problems. The process of drum bulging after catheterization, retraction after inflation, and inward movement during swallowing, proved that intratympanic pressure was influenced by nasopharyngeal pressure produced by swallowing, and that Eustachian tube itself was functioning to the pressure. Intratympanic negative pressure was proved by the movement of blue solution after the puncture of 5 atelectatic ear with effusion. And more dynamic negative pressure produced by swallowing was demonstrated in 5 other cases. The morbid adenoid with atelectatic eardrum was differentiated from the large posterior type of adenoid of the healthy eardrum, by the pendulous projection over the choana especially in swallowing. A dynamic vacuum caused by "Toynbee phenomenon" is discussed.