Volatile terpenes present in cotton plants and mill dust can cause inflammatory reactions in humans, and thus may be involved in byssinosis. Concentrations of volatile terpenes were determined in five glanded aid five glandless cultivars and lines. The major terpenes in all glanded cultivars were -caryophyllene, myrcene, -pinene, -bisabolol, -bisabolene, -humulene, and ocimene. Glandless cultivars and lines had little, if any, volatile terpenes found in genetically comparable glanded cultivars. Glandless and glanded cottons should be excellent tools for evaluating the importance of volatile terpenes in byssinosis.