Asthma patients have bronchial hyperreactivity compared with normal subjects. The pathophysiological characteristics of bronchial asthma show the reversible bronchial obstruction (air-flow limitation) caused by several physical and chemical stimuli. Thus, it is important to verify the bronchial responsiveness for diagnosis of bronchial asthma. Function testing of bronchial responsiveness is one of the bronchial reactivity tests which is important for the diagnosis of bronchial asthma as well as the judgment of severity, therapeutic effect and the differential diagnosis. Function testing of bronchial responsiveness consists of 2 major parts : 1) standard method of acetylcholine or histamine inhalation test 2) direct-writing recorder of the dose-response curves of the airway to methacholine test (Astograph).