Pathology standards were developed for classifying the pulmonary lesions and roentgenographic evidence of coal workers' pneumoconiosis (CWP). The pigmentation of the lungs, pleura, and lymph nodes in normal, smoking, and coal dust exposed populations is described, and procedures for sample collection and tissue analysis are presented. The macular, micronodular, and macronodular lesions of simple CWP, the nodules of simple and conglomerate silicosis, and the abnormalities associated with progressive massive fibrosis are discussed. Various types of emphysema, including the focal emphysema related to CWP, are delineated. Roentgenographic evaluation and classification of CWP lesions are summarized and illustrated, and the use of pulmonary function tests to assess the degree of respiratory impairment caused by CWP is reported. The authors conclude that research is needed on the progression from macular to nodular lesions in CWP and into the development of chronic obstructive pulmonary disease in coal miners. They recommend improved postmortem lung examination techniques, mandatory autopsies for deceased coal miners, and improved training in occupational pulmonary effects for pathologists.