Environmental and occupational lung diseases encompass a diverse group of lung diseases caused by the inhalation of potentially harmful substances. Although workplace regulations and the changing economy in the United States have significantly decreased incidence, these diseases remain both common and associated with significant morbidity. In addition, novel exposures continue to be recognized as new causes of disease. This review provides the medical student and clinician with a framework for approaching and categorizing environmental and occupational lung disease. It also presents an in-depth discussion of the epidemiology, biological mechanisms, diagnosis, and clinical care of some of the more commonly encountered diseases. Occupational lung diseases that affect the airways, such as work-related asthma and chronic obstructive pulmonary disease, and malignant neoplasms are covered. This review concludes with general strategies to help prevent disease incidence and progression. This review contains 1 figure, 5 tables, and 56 references. Key words: bronchiolitis obliterans, chronic obstructive pulmonary disease, irritant-induced occupational asthma, mesothelioma, occupational asthma, occupational lung disease, occupational lung neoplasm, work-related asthma