It is believed that GER can trigger asthma by the stimulation of acid-sensitive receptors in the esophagus. The aim of this study was to determine whether esophageal acid stimulation in asthmatic patients can provoke clinically detectable bronchospasm and if a possible response is correlated to bronchial reactivity. Eight patients with chronic asthma and GER disease were investigated on three occasions with a histamine challenge test followed by acid provocation of the esophagus. Assessment of bronchial function was made by FEV1, chest auscultation, and respiratory symptoms. While symptoms and signs of bronchoconstriction induced by esophageal acid stimulation were not detected clinically on any occasion, there was a significant correlation between histamine reactivity and the subclinical bronchospasm following acid provocation. It is concluded that esophageal acid stimulation during daytime in the majority of asthmatic patients is not a strong and immediate trigger of asthma.