In 63 out of 887 patients with alveolitis and pulmonary fibroses was causally found a so-called "collagenosis". A participation of the lung in such diseases is prognostically unfavourable. The changes in the framework of the lungs radiographically, functionally and morphologically cannot be separated from fibroses of other origin. The diagnosis is to be made after exclusion of other noxae and taking into consideration the appearances of the primary disease (clinic, spectrum of organs, special laboratory parameters etc.).