BACKGROUND AND OBJECTIVE: T cells play a pivotal role in initiating and orchestrating bronchial inflammation in asthma. However, little is known about changes in T cell subset in the airways. Our objective was to study whether the proportion of CD4+ or CD8+ T cells in the bronchoa1veolar lavage fluid (BALF) of bronchial asthma is different from normal subjects, and whether it is associated with clinical characteristics. METHODS: We examined the percentage of CD4+ and CD8+ cells in the BALF of 37 patients with bronchial asthma and 14 normal controls by flow cytometry. Bronchial asthma was classified as mild, moderate and severe according to bronchial hyperresponsiveness. Skin prick test and pulmonary function tests were performed. RESULTS: The percentage of CD4+ cells in BALF did not differ between asthmatics and controls, however, the percentage of CD8+ cells was significantly higher in asthmatics than contro1s, In asthmatics, the percentage of CD4+ cells and CD8+ cells did not differ between atopic and nonatopic asthmatics. The percentage of CD8+ cells in addition to CD4+ cells was correlated with the percentage of eosinophils in BALF, and the percentage of CD8+ cells also showed negative correlation with FEV, and FEF25-75% CONCLUSION: These results suggest that CD8+ cells as well as CD4+ cells are associated with airway inflammation in bronchial asthma.