Extent of nasal and maxillary mucosa lesion was estimated in 26 asthmatics using computed tomographic scan in relation to clinical features of the disease. 1. No significant differences were present in nasal mucosal thickening between atopic and non-atopic subjects. No significant differences were also present in occupancy rate of mucosa in maxillary sinuses between the two asthma types. 2. Nasal mucosal thickening was not significant different between subjects with steroid-dependent intractable asthma (SDIA) and those without SDIA. Maxillary mucosal lesions were more extensive in subjects with SDIA than in those without SOIA. However, no significant differences were observed in occupancy rate between the two types. 3. No significant differences were observed in nasal mucosal thickenings between in subjects with and without aspirin-induced asthma (AlA). Although maxillary mucosa lesion in subjects with AlA was more extensive than that in those without AlA, the differences was not significant. 4. There was not any correlation between nasal mucosal thickening and amount of expectoration per day. However, significant differences were observed in maxillary sinus lesion between subjects with less amount (<50mℓ/day) and those with large amount of expectoration (100mℓ/day≦)(p<0.002), and between subjects with moderate amount (50-99mℓ/ day) and those with large amount of expectoration (p<0.002). The results might suggest that in asthmatics with large amount of expectoration, sinus diseases affect pathophysiology of asthma, and asthmatics with large amount of expectoration should have therapy for sinus disease to improve asthmatic status.