An aqueous extract was prepared from the cotton dust 1182 which had been used for a twelve month exposure of guinea pigs. Analysis of the extract revealed the following composition: protein 2.7%, reducing sugar 12.8% and nucleic acid 4.5%. Other components included simple sugars, organic acids and inorganics. Microbiological analysis of the dust indicated typical levels of Gram negative, and Gram positive, bacteria, thermophilic bacteria, and fungi. SDS gel electrophoresis of the extract revealed multiple components with molecular sizes ranging from 15 to 66 kilodaltons. Western blot revealed that only tight of the components (molecular sizes 18 and 21 kd) reacted with serum drawn from which had been exposed for one year to airborne cotton dust. To identify these materials, the components were purified using affinity chromatography on Affigel-Conavalin A. The purified glycoprotein fraction was able to completely prevent reaction of antiserum with the cotton dust extract. Confirmation of the glycoprotein nature of the antigens was obtained by treatment, of the extract with trypsin and sodium periodate. ELISA inhibition assays further indicated that the antigens were not E. agglomerans or its LPS.