Silicosis is an occupational lung disease caused by the inhalation of respirable dust containing crystalline silica. There are two forms of the disease: nodular silicosis and silicoproteinosis (acute silicosis). Nodular silicosis (chronic and accelerated) is slowly progressing and manifests as scarring of the lung tissue. It is typically evident on chest x-ray only after 10 or more years of exposure (chronic silicosis), but may be seen after as little as five years (accelerated silicosis). Nodular silicosis may present without symptoms; shortness of breath and cough typically accompany advanced disease. Silicoproteinosis (acute silicosis), a less common form of silicosis, is an alveolar filling process which becomes evident within weeks to months after a very intense initial exposure; death usually occurs within a few years of onset. Except in acute silicosis, lung biopsy is rarely needed for diagnosis, as the radiologic picture is often sufficiently distinct to permit diagnosis of silicosis in persons with a clear history of exposure. Individuals with silicosis are at increased risk of tuberculosis and lung cancer. Silica exposure and/or silicosis has also been associated with autoimmune diseases such as lupus erythematosus, rheumatoid arthritis, scleroderma, and with glomerulonephritis. Silicosis is a progressive, incurable, and potentially fatal disease that can be effectively prevented by limiting exposure to respirable crystalline silica dust.