The presence of endotoxins in nonagricultural occupational settings and their contribution to morbidity were examined in this review. Endotoxins have been reported to affect the immune system, complement and coagulation systems, and to induce pulmonary symptoms. Associations have been reported in humans between decreased pulmonary function and airborne levels of endotoxins. Calculated thresholds of endotoxin exposures resulting in no change in lung function have been exceeded almost 1,000 fold in certain agricultural settings. Endotoxins have been extensively identified in agricultural environments as well as in industrial settings using humidifiers, air conditioners, cooling towers, and water associated processes, and in cotton, wool, and flax, machining, waste disposal, sewage, animal feed, and biotechnology industries.