To evaluate the effect of damaged bronchial epithelium on epithelial permeability and physiologic changes of the airway in patients with bronchial asthma, we measured the concentration of protein and albumin in bronchoalveolar lavage fluid (BALF), the width of intercellular junction and bronchial hyperreactivity in 22 patients with bronchial asthma and 21 healthy subjects. The results were as follows: 1) The concentration of protein in BALF from patients with bronchial asthma was higher when compared with that of normal subjects ($237{pm}182$ vs $113{pm}78;{mu}g/mL$, p<0.05), and the concentration of albumin was also higher than that of normal subjects ($116{pm}126$ vs $32{pm}88;{mu}g/mL$, p<0.05). The ratio of the concentration of protein in BALF to that in serum was increased in patients with bronchial asthma when compared with that of normal subjects ($0.35{pm}0.30$ vs $0.16{pm}0.11%$, p<0.05). 2) The intercellular junction of bronchial epithelium was widened in 14 of 20 patients with bronchial asthma, in contrast, 5 of 14 normal subjects (p<0.05). The mean width of intercellular junction was greater when compared with that of normal subjects ($1.71{pm}1.81$ vs $0.56{pm}0.85;{mu}m$, p<0.05). The width was well correlated with the ratio of protein in BALF to that of serum (r=0.3226, p=0.047) when observed in 18 patients with bronchial asthma and 10 patients with normal subjects. 3) The bronchial hyperreactivity, expressed as $PC_{20}$, was inversely correlated with the concentration of protein in BALF (r=-0.3030, p=0.038) in when observed in 18 patients with bronchial asthma and 19 normal subjects. 4) The width of intercellular junction was well inversely correlated with $PC_{20}$ (r=-0.5006, p=0.002) when observed in 19 patients with bronchial asthma and 11 patients with normal subjects. In conclusion, increased permeability and the damage of bronchial epithelium may lead to change of bronchial hyperreactivity.