Summary Background In chronic obstructive pulmonary disease (COPD) the clinical efficacy of bronchodilator therapy delivered via a nebulizer versus an aerochamber on FEV1 is controversial. No studies comparing changes in inspiratory pulmonary function parameters (ILPs) using these inhaler devices are currently available. This information might be of interest because due to dynamic bronchial compression, the relationship between the ILPs and dyspnea is more reliable than that between FEV1 and dyspnea. Therefore, our study aimed to investigate whether changes in ILPs after use of these inhaler devices were similar to the changes in FEV1 and correlate with VAS (Visual Analogue Scale). Methods Forty-one stable COPD patients participated in a crossover trial. Spirometry was performed before and after two puffs Combivent (200 mcg salbutamol and 20 mcg ipratropium per puff) using an aerochamber or 2 mL of Combivent (2.5 mg salbutamol and 250 mcg ipratropium per mL) using a nebulizer. Differences in lung function parameters and changes in VAS were measured. Results ILP values improved significantly from baseline after Combivent administration using both devices (p ≤ 0.004). With both devices, the mean percent changes were significantly greater for FEV1 than the ILPs (p ≤ 0.003), except for IC (p = 0.19). The mean VAS score did not differ significantly between the devices (p = 0.33), but significant correlations were found between the VAS and forced inspiratory flow at 50% of the vital capacity (FIF50) and peak inspiratory flow (PIF) when a nebulizer was used. With an aerochamber, no significant correlations between lung function parameters and VAS were found. Conclusions The present study demonstrates that ILPs improved significantly after using either device. Although significant correlations were found between the VAS and FIF50 and PIF for the nebulizer, in stable COPD patients, the pMDI plus spacer is a better route of administration than a nebulizer.