As an inflammatory airway disease, asthma is expected to be associated with an increase in airway blood flow. We therefore compared airway mucosal blood flow (Q˙ _aw) among normal subjects (n = 11) and patients with stable asthma receiving (n = 13) or not receiving (n = 10) long-term inhaled glucocorticosteroid (GS) therapy. Q˙ _aw was calculated from the uptake of dimethyl ether in the anatomic dead space minus the most proximal 50 ml (DS), and expressed as blood flow per ml DS. Mean ( ± SE) Q˙ _aw was 38.5 ± 5.3 μ l · min^{− 1} · ml^{− 1} in normals, 68.2 ± 7.9 μ l · min^{− 1} · ml^{− 1} in GS-naive asthmatics (p < 0.01), and 55.4 ± 5.3 μ l · min^{− 1} · ml^{− 1} in GS-treated asthmatics (p < 0.05). Ten minutes after administration of 180 μ g albuterol by metered dose inhaler, mean Q˙ _aw increased by 83 ± 26% in normal subjects (p < 0.01), but did not change significantly in GS-naive ( + 5 ± 8%) or GS-treated ( + 32 ± 15%) asthmatics. These results demonstrate that Q˙ _aw is increased in stable asthmatics and resistant to further increase by a standard inhaled dose of a beta-adrenergic agonist.