Interstitial lung diseases (ILD) associated with connective tissue disorders differ from idiopathic ILD in several aspects, although most of them are comparable. In most patients, ILD occurs during the course, or at the time of diagnosis of connective tissue disease. Opportunistic pulmonary infections, together with adverse effects of treatment should always be discussed. The prevalence of ILD varies among the different connective tissue disorders. Thus, ILD is frequently encountered in patients with systemic sclerosis and to a lesser degree in patients with myositis. As compared to idiopathic ILD, histopathological aspects of ILD associated with connective tissue diseases are more frequently those of non-specific interstitial pneumonia, whereas usual interstitial pneumonia is rare. Other ILD, such as organized pneumonia, interstitial lymphoid pneumonia, diffuse alveolar damage and alveolar hemorrhage are occasionally encountered. ILD must be detected early in the course of collagen disorders by performing computed tomodensitometry and pulmonary function tests. The prognosis of connective tissue associated ILD is better than that of idiopathic ILD. The treatment requires corticosteroids and/or immunosuppressants, depending on the nature of the associated connective tissue disease and ILD progression.