The CT diagnosis of nonneoplastic tracheal disease is based on the appearance of the tracheal wall on inspiratory scans, changes on the tracheal wall with expiration, and the location and extent of tracheal abnormalities. Recognizing specific tracheal wall abnormalities is of primary importance because specific diseases tend to affect different components. By noting the portion affected and its abnormal characteristics, a diagnosis may often be suggested. In this pictorial essay, alterations in the appearance of the tracheal wall in certain diseases will be emphasized.