Cotton bract and other plant parts can be contaminated with gram-negative bacteria. These bacteria and their associated endotoxins have been related to lung dysfunctions in some cotton textile mill workers. Research on endotoxins at the Southern Regional Research Center (SRRC) has concentrated on two major areas: (1) development of a chemical and/or instrumental procedure for the detection and quantification of bacterial cell wall products (endotoxins, lipopolysaccharides) in cotton dust; and 2) development and evaluation of processes for the effective deactivation and/or elimination of endotoxins, a suspected causative agent of byssinosis, from cotton. Current research activities include attempts to quantify endotoxins by measuring 3-hydroxymyristic acid in cotton using high performance liquid chromatography (HPLC) and preliminary results using gases and liquids to deactivate cotton dust. Results of a parallel study on measurement of condensed tannins in cotton bracts obtained from different areas of growth will be presented in light of their relationship to endotoxin levels in these cottons.