Clinical features of asthmatics with a low % FVC (<80%) were studied in relation to airway inflammation and clinical asthma types. 1. Twenty four (75.0%) of the 32 subjects with a low % FVC had steroid-dependent intractable asthma. 2. A significant association between % FVC value and clinical asthma type was found. The value of % FVC was significantly lower in subjects with type II asthma (bronchiolar obstruction), in which significantly decreased proportion of lymphocytes,and significantly increased proportion of neutrophils in bronchoalveolar lavage (BAL) fluid were observed, than in those with type la-1 (simple bronchoconstriction) with (P<0.001) and without glucocorticoid therapy (P<0.02). 3. The % FVC value was significantly improved after treatment in type lb (hypersecretion) with BAL eosinophilia, but not in those with type II with BAL neutrophilia. These results demonstrate that marked decrease of % FVC in patients with asthma correlated with airway inflammation, and that airway reversibility by medication is very low in patients with type II asthma.