Two types of Eustachian tube dysfunction can result in otitis media: obstruction and abnormal patency. Obstruction may be either functional or mechanical. Functional obstruction can result from persistent collapse of the Eustachian tube due to increased tubal compliance, an inadequate active opening mechanism, or both. Mechanical obstruction may be the result of either intrinsic or extrinsic factors. Otitis media can result from inadequate ventilation of the middle ear or entry of unwanted nasopharyngeal secretions into the middle ear (by aspiration, insufflation, or reflux), or both. An understanding of these concepts of Eustachian tube function and otitis media can then be related to the rationale for nonsurgical and surgical management and prevention of middle-ear disease.