In 715 patients with collagen vascular diseases, interstitial lung disease and pulmonary hypertension were found to be important causes of death (37.5% and 6%, respectively). The prognosis of interstitial lung disease associated with collagen vascular disease was better than that of idiopathic interstitial pneumonia; patients with the latter were more likely to experience exacerbations. A distinct subgroup of patients with dermatomyositis and interstitial lung disease with a rapidly progressive course was characterized by mild muscle symptoms, low levels of creatine phosphokinase and negative tests for anti-Jo-1 antibody. CT scores and analysis of bronchoalveolar lavage fluid proved to be of some value in predicting outcome. Measurement of IL-6 in bronchoalveolar lavage fluid and local immunostaining for this pro-inflammatory cytokine were helpful in evaluating responses to therapy.