Collagen vascular diseases are a group of immunologically mediated diseases, and may be associated with both localized and diffuse pulmonary lesions. The latter lesions account for a significant part of the diffuse interstitial lung disease spectrum. The pulmonary changes of rheumatoid arthritis and systemic lupus erythem atosus (SLE) are the most widely recognized. However, other collagen vascular diseases, such as systemic sclerosis (scleroderma), ankylosing spondylitis, and dermatomyositis-polymyositis (DPM), may also present with pulmonary involvement. Collagen vascular disease should be considered in the differential diagnosis of interstitial lung disease. Almost all collagen vascular diseases are ultimately associated with a diffuse interstitial fibrosis resembling usual interstitial pneumonia (UIP), but rheumatoid arthritis is most commonly associated with UIP-like disease. Common presentations in other diseases include pleuritis, capillaritis, and pulmonary hemorrhage in SLE; pulmonary hypertension in scleroderma; and bronchiolitis obliterans in DPM.