Lymphocyte subpopulations in peripheral blood were examined in asthmatic children, using fluorescent monoclonal antibodies. The patients were divided into three groups: Group I, no attack (FEV1.0% > or = 80% group), Group II, no attack (FEV1.0% < 80% group) and Group III, asthmatic attack group. The percentage of CD3HLADR/CD3 in the Group II and Group III were 5.58 +/- 3.59 and 5.44 +/- 4.34, respectively, which were significantly higher than that in the Group I subjects (2.70 +/- 2.17). This finding suggests that the patients with long lasting bronchial obstruction may have chronic inflammation in the airway even in the remission stage of asthmatic attacks.