In the article we outlined the basic principles of some recent methods of lung function testing, suitable for the assessment of airway obstruction in children and adolescents. There is also a brief description of various methods, normal values expressed in a form of regression equations, significance of different methods for the assessment of airway obstruction in patients with respiratory diseases and in children from a region with increased levels of air pollution. Among the various functional indices we found the most sensitive for the assessment of airway obstruction maximum expiratory flow rates measured at lower lung volume levels. Airway conductance appeared as the most sensitive method for the evaluation of bronchodilation following inhalation of some drugs. The measurements of airway conductance in a body plethysmography during normal quiet breathing and of maximum expiratory flow rates from flow-volume curves represent the basic methods for the detection of airway obstruction, i.e. in the larger central airways, and in the peripheral airways respectively.