The frequency of drug-induced damage to the lung in inpatients is estimated to be about 10%. Pathoanatomically, varying damage patterns result, ranging from acute pulmonary edema via inflammatory reactions to pulmonary fibrosis. The ATS/ERS 2001 classification, which is based on the suggestions made by Liebow 1969, is an accepted system for classifying findings according to recurring patterns. Generally, there are no specific morphological findings which allow safe conclusions on possible administered drugs. Clinical information is mandatory. Differentiation from pulmonary alterations due to the underlying disease is often difficult. In daily routine diagnostics, it is important to consider iatrogenic causal factors in cases of "undetermined pulmonary disease".