Bronchial obstruction evaluation is usual problem of clinical practice. Solution of this problem sometimes becomes difficult regardless of obvious methods and new technologies introduction. Incorrect bronchial obstruction diagnostic may determine incorrect treatment, case prognosis and may determine loss of disease control. Clinic of Pulmonology of Vilnius University Hospital "Santariskiu klinikos"carried out study about this problem. Preliminary pilot data are presented. Aim of study was comparison of different methods of bronchial obstruction evaluation. In 2002 50 patients with bronchial obstruction diagnosis (bronchial asthma and COPD) were observed. The following tests were performed: standard questionnaire, physical examination, PFT - spirometry, body plethysmography, blood gas analysis. There were analyzed FEV(1)/FVC, FEV(1), FEF(25-75%), RV/TLC, Raw, PaO(2), PaCO(2), SpO(2), pH. This study data shows that for majority (88%) of patients bronchial obstruction can be evaluated by spirometry test, however overall evaluation of patient status (extensive anamnesis and objective evaluation) is also important while determining bronchial obstruction, since 84% of patients complain on dyspnea and for 72% of patients obstruction-specific symptoms are observed during evaluation. Part of patients requires extended lung function evaluation (12%), which confirmed obstruction for 94% of patients. Established strong correlation between measurements of extended lung function evaluation and spirometry measurement FEF(25-75%) shows high informativeness in evaluation of bronchial obstruction.