A protocol was developed for indirect ELISA of Lipid A in cotton dust extracts and in treated and untreated cells of E. agglomerans and P. syringae. Boiling the cells for 15 min prior to assay of the resulting at cells concentrations of 10⁴ per ml. This treatment was easily adapted to the extraction and ELISA of Lipid A in cotton dust. Chemically treated dust extracts and the two bacteria were only successful with the bacteria. Improvements are needed to make the assay fully quantitative with cotton dust extracts.