The pleura is comprised of a visceral and parietal layer. The potential space between the two is normally filled with a small amount of physiologic fluid. The visceral pleura invaginates to form fissures, and collectively the pleura allows the lobes of the lungs to move relative to each other and the chest wall during respiration. In diseased states, this potential space can fill with abnormal amounts, or atypical types, of fluid. The pleura can become thickened, often in response to infection, inflammation, or exposures. Tumors can also arise from the pleura. Malignant pleural mesothelioma is a particularly aggressive primary tumor of the pleura, which is associated with asbestos exposure. Owing to lymphatics and vascularity, the pleura can also be the site of tumors deposits from malignancies originating outside the pleura. Ectopic tissues may also be found within the pleural space. The chest wall is external to the pleura, and it is comprised of skin, various fat layers, fascia, muscles, nerves, lymphatics, and bone. Primary tumors, both benign and malignant, and metastases can involve the various layers of the chest wall. There are a few specific pathologies that are unique to the chest wall, which will be reviewed. As a final category, there are a few disease entities, mostly infection and cancer, which can affect both the pleura and the chest wall simultaneously.