We present two cases of an uncommon lung disease. The considerable decrease in respiratory function was in sharp contrast with the moderate changes seen in the lung. Whereas the radiographs only revealed a milky and a slightly reticular cloudiness of the lungs, pulmonary vital capacity and compliance were reduced to one half of the standard value. Open lung biopsies were performed. Histological examination showed a fibrosing alveolitis with considerable response and foreign body reaction of the alveolar and interstitial macrophages. Intraalveolar and interstitial granulomas included macrophages and multinucleated giant cells of the foreign body type. They frequently enclosed PAS-positive material. Ultrastructural examination revealed distinct lysosomal inclusions in the macrophages and giant cells. Similar inclusions were induced in guinea pigs by hair-spray components. These findings led to the diagnosis of an exogenous thesaurosis of the lung. Prolonged and excessive exposure to hair-sprays could be established in both cases. Upon termination of the exposure, a marked improvement occurred in both patients within half a year. Extreme exposure to hair-spray may cause alterations of the lung parenchyma, including a so-called "hair-spray lung". The present report is directed towards a better understanding of this particular disease which is one of the numberous conditions induced by the increasing air pollution.