Experience from animals exposed to cotton dust demonstrates that different mediators are released. In an attempt to elucidate the relevance of these observations for humans, cotton cardroom workers were pretreated with different anti-inflammatory agents on a double blind basis. Respiratory function was determined before and after tie Monday work shift. A bronchodialator was administered after the post exposure measurements. Indomethacin prevented bronchoconstriction. Salbutamol releaved bronchoconstriction after work.