The trachea is a cartilagenous and membranous tubular midline structure with parallel walls. Tracheal deviation may be causes either by traction toward the diseased hemithorax or by compression toward the normal side. Unless an obvious mass is observed radiographically, occasionally it can be difficult to decide whether the trachea has been pushed or pulled from its normal position in the mediastinum. We studied the differences between tracheal deviation patterns in 23 patients with fibroatelectatic pulmonary tuberculosis and 35 patients with elongated and dilated aortas. In cases of retraction of the trachea by fibroatelectaic pulmonary tuberculosis, the diameter of the deviated segment was greater than that of the normal segment and deviation of the wall adjacent to the fibroatelectasis from its normal position was greater than that of the opposite wall. In cases of compression of the trachea by the elongated and dilated aorta, the diameter of the diviated segment was smalle than that of the normal segment and deviation of the wall adjacent to the aortic arch from its normal position was greater than that of the opposite wall. We conclude that these differences between tracheal deviation patterns are useful signs for discrimination retraction from compression. Thus when the trachea is trachea is retracted, the deviation of the juxtalesional wall is greater than that of the lesion-free wall, and vice versa.