The authors reviewed nonasbestos etiologies and diagnostic issues related to pleural plaques. Through searches of PUBMED and DIALOG using the term pleural plaques, they identified 125 articles. The authors found additional references by reviewing citations of these 125 articles. Exposure to nonasbestos agents (eg, erionite, silicates, manmade fibers) was cited as a possible factor in plaque development, although this association was based on limited data; empyema, tuberculosis, rib fractures, and hemothorax also were cited as potential etiologies. Rib companion shadows, fat, intercostal vessels, and muscles can appear as plaques; thus, radiographic diagnosis requires careful evaluation. Chest x-rays show large false negative and varying false positive rates. The terms calcification and thickening often were used as synonymous with plaques; however, these terms have different meanings. The authors concluded that plaques may be associated with nonasbestos exposures and certain medical conditions. Without a thorough exposure/medical history, plaque reports can be misleading.