There is an increased incidence in gastroesophageal reflux (GER) in subjects with asthma. The cause-effect relationship remains controversial. We compared 15 subjects with mild asthma to 15 control subjects (nonasthmatic) to ascertain if GER might be induced by bronchospasm. Continuous monitoring of lower esophageal sphincter pressure and pH at 5 cm above the lower esophageal sphincter was performed in seated subjects for 3 hours in total: 1 hour of baseline measurements, 1 hour of methacholine inhalation with a dosimeter, and 1 hour after the inhalation of 200 micrograms of salbutamol (albuterol). During bronchospasm, subjects with asthma had more episodes of GER (3.9 +/- 1.5) and dropped their pH to lower levels (pH 2.23 +/- 0.3) than did the control subjects (0.8 +/- 0.3 episodes, pH 3.22 +/- 0.3) p less than 0.05. We conclude that in these subjects with mild asthma, methacholine-induced bronchospasm produced GER episodes of greater frequency and severity.