Eight volatile oil constituents of the cotton plant, guaiene, phellandrene, bisabolene, gossonorol, caryophyllene, caryophyllene 9-oxide, terpinene, and (Y) terpinene were added to cultures of rabbit pulmonary alveolar macrophages and culture supernatants were monitored for prostaglandin F₂ (PGF) content. Of these eight oils, only gossonorol induced a significant (statistically and quantitatively) production of PGF. Gossonorol a cotton gland constituent was found to be water soluble at approximately 56 ppm but soluble in natural surfactant (lung lavage fluid) at 259. Thus, gossonorol, inhaled as bract particles, could theoretically contribute to the bronchial constriction of byssinosis. Rabbits were therefore exposed to nebulized gossonorol and the PGF content of their lung lavage fluid was monitored. A statistically significant increase in PGF content of lavage fluid from gossonorol treated animals was observed. However, PGF content remained within "normal" levels reported by others. Thus, although our in vitro data are very suggestive of a role for gossonorol in byssinosis, our in vivo data are inconclusive.