Increased concentrations of several eicosinoids have been found in the airways of animals challenged with cotton dust extract (CDE) but the cells responsible and the compounds in CDE responsible for the release are not known. We examined the effect of endotoxin on AA metabolism by airway epithelium using bovine tracheal cells grown in culture. Endotoxin caused a time- and does-dependent release of AA from airway cells with a maximum release occurring at 1 minute at endotoxin concentrations greater than 10 ng/ml. AA release by endotoxin was not inhibited by indomethacin, ETYA, cycloheximide, neomycin or pertussis toxin. These data demonstrate that endotoxin at high concentrations increases nonmetabolized AA release by bovine tracheal epithelial cells by a mechanism different from tannin-induced AA release.