Effects of long-term glucocorticoid therapy on airway inflammatory cells were examined in 40 patients with bronchial asthma. 1. The dose of glucocorticoids required by asthmatic patients tended to increase and the level of serum cortisol tended to decrease with prolongation of the period of glucocorticoid therapy. 2. The proportion and number of lymphocytes in bronchoalveolar lavage (BAL) fluid decreased with prolongation of the period of glucocorticoid therapy. The proportion of BAL lymphocytes in asthmatic patients treated with glucocorticoids for more than 5 years was significantly lower than that in those treated for less than 4.9 years. 3. The proportion and number of BAL neutrophils increased with prolongation of the period of glucocorticoid therapy and the proportion of BAL neutrophils in patients treated with glucocorticoids for more than 10 years was significantly higher compared with those treated for less than 9.9 years. These findings indicate that long-term glucocorticoid therapy induces changes in airway inflammatory cell profiles, with a decrease in the number of lymphocytes and increase in the number of neutrophils.