Cottons from glanded and glandless cotton plants were carded in an experimental cardroom. Workers from a cotton industry were exposed to the dusts in the cardroom during a four hour period. Measurements of the respiratory function and blood neutrophils were made before and after the exposure. Dust from the glanded cotton contained 0.4 pq of endotoxin per mg and dust from glandless cotton 0.7 µg/m³. No difference in the FEV(1) decrease over shift was found at equivalent dust endotoxin levels.