It has been demonstrated that the lack of epithelium in healthy airways from different species modifies the reactivity of tracheobronchial smooth muscle. In the present work we have investigated the effect of airway epithelium removal in tracheal chains from guinea pigs sensitized to ovalbumin by inhalatory route and unsensitized animals. We found that in both groups the mechanical removal of airway epithelium produced an increase in the tracheal sensitivity and maximum contractile response to histamine. The greatest responses were observed in epithelium-lacking sensitized tracheas. These findings, at least in vitro, support the idea that the damage of respiratory epithelium plays an important role in modulating the airway reactivity and this is more noteworthy in tracheal chains from previously sensitized guinea pigs.