Aim. To develop a procedure for evaluating the efficacy of antiiflammatory agents in mild persistent bronchial asthma. Materials and methods. 76 patients with mild bronchial asthma were given long acting theophylline. If a complete clinical and functional effect was absent, the inhaled glucocorticosteroid budesonide was added to the therapy. Before and after therapy, the forced expiratory volume per second and forced vital capacity (FVC) were measured many times within 24 hours, by using two procedures: 1) that involving morning and diurnal tests using short acting B2-agonists and 2) that without a bronchodilator. The time of onset of the plateau of values of different functional indices obtained during monitoring and their dispersion in the stable state were automatically calculated. The reliability of indices for evaluating the efficiency of antiinflammatory therapy was compared. Results. There were great differences in the patients' response to therapy: a complete clinical and functional effect of therapy with long acting theophylline alone (n = 9) and in combination with budesonide (n = 56). Moreover, therapy-resistant patients (n = 11) were identified. When a complete therapeutic effect was achieved, the clinical symptoms of the disease disappeared before the onset of the plateau of values of the most reliable functional indices. A comparative analysis of the indices has indicated that the ratio of the morning value of FVC measured just after awakening to its best personal value throughout the study was most convenient for the patients and reliable. Conclusion. The authors propose to use the index "ratio of the morning value of FVC measured just after awakening to its best personal value the percentage", by calculating the dispersion of this index, which characterizes the steady state of the expiratory respiratory system in order to evaluate the efficiency of antiinflammatory therapy for bronchial asthma and to solve other problems that require functional monitoring.