Mucus hypersecretion was clinically analyzed in 46 adult patients with bronchial asthma, including 22 with steroid-dependent intractable asthma (SDIA). A large amount of expectoration, over 50 ml/day, was observed in 16 of these patients (34.8%), of whom 12 (75.0%) had SDIA and 13 (81.3%) were women. The mean amount of expectoration increased with increasing patient age, although no significant difference was found among the six age groups. A large amount of expectoration (over 50 ml/day) was clearly correlated with an increased proportion of eosinophils in bronchoalveolar lavage (BAL) fluid. The proportion of BAL eosinophils was significantly higher in patients with expectoration between 50 and 99 ml/day (p < 0.05) and over 100 ml/day (p < 0.01) than in patients whose expectoration volume was between 30 and 49 ml/day. These results show that in bronchial asthma patients, mucus hypersecretion is more often observed clinically in those with SDIA and in women, and that this hypersecretion is closely correlated with BAL eosinophilia, which is a feature of the pathophysiological changes that occur in the airways of these patients.