KCa3.1 is a calcium activated potassium channel expressed in several tissues and cell types but its role in the function of airway epithelia is poorly understood. We have previously demonstrated that KCa3.1 activity is essential for calcium-activated chloride secretion in mouse intestine and its absence reduces water faecal content (Flores et al., 2007). We aim to understand the role of Kca3.1 in the airway epithelia using the KCa3.1-/- mouse and the selective inhibitor TRAM-34 in human and mouse cells. We measure short-circuit currents by Ussing chamber studies in native mouse tissues and human bronchial epithelial cells. Ciliary beating frequency (CBF) was studied in primary airway cultures using the SAVA Sisson Ammons video analysis. We also determined the effect of KCa3.1 inhibition in a mouse model of chronic asthma induced by ovalbumin (0.5mg/mL) instilled intranasally during 9 weeks. All animal procedures were performed according to institutional regulations for animal welfare. Electrophysiological measurements in freshly isolated tracheas from KCa3.1-/- mice showed a significant reduction of ENaC-mediated sodium absorption (19.4±5 vs 3.7±4 µA cm-2 for KCa3.1+/+ and KCa3.1-/- respectively). This reduction was not explained by decreased expression of ENaC subunits, evaluated by qRT-PCR. Reduction in sodium absorption was mimicked in human bronchial epithelial cells when incubated with TRAM-34 (3.1±0.5 vs 1.6±0.3 µA cm-2 for control and TRAM-34 incubated cells respectively). CBF in primary epithelia airway cultures from mice was increased after UTP stimulation (1μM) in KCa3.1-/- (28.6%) and in KCa3.1+/+ cultures treated with TRAM-34 (100nM) (16.3%) compared to KCa3.1+/+ cultures (4.2%) obtained from wild type animals. Finally, we analysed the impact of KCa3.1 silencing in a mouse model of chronic asthma. We found that the development of asthmatic features such as goblet cell hyperplasia, increased collagen deposits, airway epithelium thickening and mast cell infiltration of airway tissues was attenuated in KCa3.1-/- mice. Our results demonstrate that KCa3.1 inhibition reduces sodium absorption. This effect is independent on changes in ENaC expression and might be explained by changes in cell membrane potential that do not favour the electrochemical potential for sodium entry. Increased CBF could benefit mucociliary clearence, but the mechanistics of such increased activity are being explored. All these changes on epithelial function can help to diminished asthma features in our animal model of the disease. Finally, KCa3.1 inhibition could help in the management of cystic fibrosis disease that presented increased sodium absorption. The therapeutic use of KCa3.1 is further supported by the fact that its inhibition does not produce severe phenotypes in KCa3.1-/- mice.