The aim of this study was to evaluate the occurrence of interstitial lung diseases (ILD) in Germany. Therefore members of the WATL developed a questionnaire which was sent to pulmonary and other physicians who may encounter patients with ILD. In 1995 altogether 234 patients (105 males, 129 females, mean age 51 years, minimum 12, maximum 88 years) were referred to the registry. 126 of these patients were non-smoker, 58 ex-smoker, 45 smoker and in 5 patients no information was given. The following ILD were reported: sarcoidosis (n = 83, 36 males, 47 females), idiopathic pulmonary fibrosis (n = 76, 35 males, 41 females), idiopathic pulmonary fibrosis (n = 76, 35 males, 41 females), alveolitis (n = 31, 12 males, 19 females), bronchiolitis obliterans organizing pneumonia (n = 16, 6 males, 10 females) and others (n = 28, 16 males, 12 females). These preliminary data show that sarcoidosis (35%) and idiopathic fibrosis (33%) were the most frequently registered ILD.