BACKGROUND: Exercise is a very common precipitant of asthma. Broncho-constriction associated with exercise can occur in 75~90% of individuals with asthma. The estimated prevalence ( 30~85% ) of gastroesophageal reflux ( GER ) in patients with asthma is significantly higher than in general population. We performed pH monitoring during the exercise in order to evalute whetherexercise induced asthma EIA ( 6 men, 12 women ) were studied. Monitoring of intraesophageal pH, ECG and spirometry was done for 1 hour before treadmill exercise. After baseline monitoring, subjects underwent symptom-limited treadmill exercise with Bruce protocol and continuous monitoring for 60 min after exercise. Spirometry was done at baseline prior to exercise, and repeated every 10 min after full exercise for 60 min. RESULTS: Exercise-induced bronchoconstriction was noted in 15 patients, who performed MBPT and 12 patients confirmed for bronchial asthma and 3 patients were diagnosed exercise-induced astham. Five 15 EIA patients demonstrated a pathologic degree of GER. CONCLUSION: We suggest that GER may be one of pathophysiologic factors of ELA and evoke further concentration on the GER in the EIA patients.