Patients with obstructive lung diseases commonly undergo bronchodilator reversibility testing during examination of their pulmonary function by spirometry. A positive response is defined by an increase in forced expiratory volume in 1 s (FEV₁). FEV₁ is a rather non-specific criterion not allowing the regional effects of bronchodilator to be assessed. We employed the imaging technique of electrical impedance tomography (EIT) to visualize the spatial and temporal ventilation distribution in 35 patients with chronic obstructive pulmonary disease at baseline and 5, 10, and 20 min after bronchodilator inhalation. EIT scanning was performed during tidal breathing and forced full expiration maneuver in parallel with spirometry. Ventilation distribution was determined by EIT by calculating the image pixel values of FEV₁, forced vital capacity (FVC), tidal volume, peak flow and mean forced expiratory flow between 25% and 75% of FVC. The global inhomogeneity indices of each measure and histograms of pixel FEV₁/FVC values were then determined to assess the bronchodilator effect on spatial ventilation distribution. Temporal ventilation distribution was analyzed from pixel values of times needed to exhale 75% and 90% of pixel FVC. Based on spirometric FEV₁, significant bronchodilator response was found in 17 patients. These patients exhibited higher post-bronchodilator values of all regional EIT-derived lung function measures in contrast to 'non-responders'. Ventilation distribution was inhomogeneous in both groups. Significant improvements were noted for spatial distribution of pixel FEV₁ and tidal volume and temporal distribution in 'responders'. By providing regional data, EIT might increase the diagnostic and prognostic information derived from reversibility testing.