Bronchial epithelial cells may be involved in the pathogenesis of asthma releasing several inflammatory mediators such as interleukins and lipoxygenase products. In this study we evaluated the spontaneous and A23128‐induced release of IS‐HETE, PGE2 and fibronectin as well as the spontaneous expression of HLA‐DR and ICAM‐1 molecules by bronchial epithelial cells obtained by bronchial brushing from 35 asthmatic and 27 normal subjects. The release of fibronectin and 15‐HETE was studied using the EIA and RIA techniques. The expression of HLA‐DR and ICAM‐1 molecules was studied using the APAAP and the immunofluorescence methods. Bronchial epithelial cells from asthmatics released higher amounts of IS‐HETE and fibronectin both spontaneously (p <0.002, p <0.05, respectively) or after stimulation with calcium ionophore compared with normals. On the other hand, PGE2 release was significantly higher only after stimulation with calcium ionophore (p <0.002). The spontaneous expression of HLA‐DR and ICAM‐1 (p <0.001) was significantly higher on epithelial cells from asthmatics than in normal subjects. Finally, the severity of asthma significantly correlated with the release of LS‐HETE (p<0.02) and the expression of HLA‐DR and ICAM‐ I respectively (p <0.001 and p <0.002, respectively). This study indicates that bronchial epithelial cells are in an activated state in asthma and that the degree of activation is correlated to the severity of the disease.