Pulmonary elastic fibers in a patient with panacinar emphysema due to alpha-1-antitrypsin deficiency and three patients with centriacinar emphysema related to anthracosis were studied by electron microscopy and by light and electron microscopic immunohistochemistry for elastin. Four types of abnormal elastic fibers were found: (1) finely disrupted fibers, (2) fibers with vacuolar changes and deposits of electron-dense granular material, (3) accumulations of small, rounded amorphous components of elastic fibers near bundles of microfibrils, and (4) large, confluent masses consisting mainly of aggregates of irregularly and compactly arranged, small-sized amorphous components. The amorphous components in these four types of abnormal elastic fibers tended to stain evenly with antielastin antibody. This is attributed to greater penetration of antielastin antibody into fibers that were incompletely polymerized because of immaturity or hydrolytic damage. Finely disrupted fibers were frequently found in the patient with panacinar emphysema and were presumed to have been damaged by elastase. The other three types of elastic fibers were frequently found in the patients with centriacinar emphysema. The vacuoles and electron-dense deposits in elastic fibers probably represented the consequence of damage to elastic fibers. The small round amorphous components in elastic fibers might be formed from abnormal elastogenesis. The large, confluent elastic masses were thought to be formed by the aggregation of elastic fibers in areas of coalescence of alveolar walls undergoing structural remodeling.