Abnormal patency of eustachian tube may result from many factors which can be classifed into two types: organic changes and functional changes. In the case of organic changes, there exist all kinds of diseases of the surrounding and near the regions of the eustachian tube such as atrophic rhinitis, pharyngitis, or chronic catarrhal otitis media. Besides, the local tissue atrophy after the nasopharyngeal operation and radiotherapy with large dosage, or cicatricial contracture and neuroparalysis may make the eustachian tube lose its normal state of closing, giving rise to prolonged patency. Functional changes like severe nervousness may make the muscle groups controlling the opening of the eustachian tube hypertonic. In this case, gradual spontaneous recovery is possible after the removal of mental stress.