Mucus hypersecretion is associated with a number of chronic obstructive respiratory diseases, in particular chronic bronchitis and asthma. Both pathologic and epidemiologic studies suggest that cotton textile workers develop chronic bronchitis and bronchospasm as a result of work in the textile industry. In order to investigate the possible role of cotton bract extract (CBE) in the mucus hypersecretion of these workers, we studied CBE's effect on mucous glycoprotein (MGP) release from human airways (HA) in culture. CBE in solution at different concentrations were added to HA, which were secreting (3)H-glucosamine MGP. CBE in concentrations of 1mg/ml to 7mg/ml caused a dose related increase in MGP release (35 to 85% above control; n=5) which was significantly above the control secretion level (p<0.001). After the initial response to CBE the airways returned to baseline secretary status within 16 to 24 hours after exposure. Thus, CBE is a potent mucous secretagogue.