Objective: To observe the relationship of deep-slow respiratory pattern and respiratory impedance(RI) in patients with chronic obstructive pulmonary disease (COPD). Methods: RI under normal respiration and during deep-slow respiration was measured one after the other with impulse oscillometry for 8 patients with COPD and for 9 healthy volunteers as control. Results: When respiration was changed from normal pattern to the deep-slow pattern, the tidal volume increased and respiratory frequency significantly decreased in both groups (P