Cellular composition of bronchoalveolar lavage (BAL) fluid was examined in 11 elderly asthmatics over the age of 70, and the results were compared with those of 11 younger asthmatics under the age of 50. In the subjects with mild asthma, the proportion of BAL cells in the elderly subjects was 86.2% macrophages, 11.0% lymphocytes, 1.9% neutrophils, 0.9% eosinophils and 0.08% basophilic cells. The proportion of neutrophils and eosinophils in the BAL fluid was slightly higher in younger subjects with mild asthma compared with that in elderly subjects, although no significant difference was found between the two groups. In subjects with severe asthma, the proportions of lymphocytes, neutrophils, eosinophils and basophilic cells were more increased in both younger and older patients compared to those with mild asthma, and a significant increase in the number of BAL eosinophils was found in younger subjects with severe asthma compared to those with mild asthma (p < 0.05). However, no significant difference was present in the proportion of BAL cells between younger and older patients with severe asthma. The results reveal that BAL cells are more increased in subjects with suvere asthma than in those with mild asthma in both younger and older subjects, and show the possibility that this increase is more predominant in neutrophils in older subjects and in eosinophils in younger subjects.