Computed tomographic (CT)-anatomic correlation of the lung was performed on young Yorkshire pigs. After in vivo CT, the lungs were removed, fixed, and dried. The lung specimens were studied with CT and on several specimens, bronchography and arteriography also were done to establish the normal anatomy. Subsequently, the specimens were sliced at corresponding levels of the CT cuts and histology was done as needed. The lobules in the pig lung are very well demarcated. On the specimen radiographs with bronchography and in vivo CT in pulmonary edema, "sublobular units" can be readily identified that are rather uniform in size. On the in vivo CT with the standard algorithm, the relationship between the branches of the pulmonary artery and bronchus can be shown to the level of segmental bronchi. With the bone detail algorithm, vessels are clearly shown and lobar bronchi become visible. On in vivo CT, the lobular demarcations cannot be seen in the normal pig but clearly are visible in pulmonary edema. In cases of pulmonary edema, in addition to the lobules, the sublobular units and the sublobular bronchi, which measure .5 to .7 mm in diameter, also can be appreciated. Because of the well-developed pulmonary lobules and the uniformly sized sublobular units, the Yorkshire pig is potentially a good model for radiologic-pathologic correlation, particularly of airspace disease.