There has been few reports about the relation between asthmatic symptoms and MEFVC. In this study, we performed MEFV maneuvers for asthmatic patients irr order to clarify the relations between mild asthmatic symptoms and MEFV curves, and the relation between the effect of the inhalation provocation test and MEFV curves. The results obtained were as follows; 1. There was a characteristic difference in flow rates at high lung volumes after peak flow rate level in MEFVC between symptom-free period and the day when wheezing was detected. 2. The MEFV pattern was compared with the effect of the inhalation provocation test by housedust extracts. Before the inhalation provocation test, the MEFVC showed a reduction in the flow rates at all the lung volumes, especially the flow rates at the lung volumes after the peak flow rate level suddenly fell down remarkably. After the inhalation provocation test, the MEFVC showed a reduction in the flow rates all the more at all the lung volumes and the MEFV pattern looked like squashed, and the FVC was also reduced.