Which course of action should be taken during the incidental finding of pleural thickening on chest X-ray? Aftereffect, without consequence, of an injury of the pleura, or potentially serious subclinical pathology? The differential diagnosis is wide, the radiograph nonspecific and the interobserver variability significant. In the absence of epidemiological studies and guidelines, the history and clinical examination remain the main factors in dictating investigations and management. Apical pleural thickening, which is nonspecific in the absence of parenchymal lesions, does not influence treatment recommendations for tuberculosis. Pleural plaques do not appear to increase the risk of cancer associated with asbestos and, thus, do not modify post-exposure follow-up. Incidental finding of pleural thickening remains a gray zone that opens the door to new studies.