The association between gastroesophageal reflux (GER) and asthma is not fortuitous. The objective of our study was to test a group of children with asthma by, 24 hr gastroesophageal pH monitoring and to relate the results to the patients medical history and clinical data. We studied 77 children aged from 39 to 170 months suffering from particularly recurrent and/or therapy-resistant asthma. Medical history data were collected for each patient and included: severity and characteristics of respiratory symptoms, presence, if any of allergy; presence, if any, of GER-related symptoms; and presence, if any, of esophagitis-related symptoms. Esophageal pH was measured by 24 hr computerized monitoring of the main measures in all patients. Forty-seven children were also examined by gastroesophageal endoscopy. The prevalence of GER was 61% on the basis of the reflux index (cutoff: 4.2%). Gastroesophageal reflux in these asthmatic children was characterized mainly by short-lasting daytime episodes. The patients tended to present GER mainly associated with vomiting but not with signs and symptoms of esophagitis. The short-lasting nature of the reflux episodes demonstrates good esophageal clearance. The time of onset of respiratory symptoms (day/night) was not associated with any particular type of GER, the severity of which tends to be proportional to the seriousness of the asthma. No correlation was found between GER and allergy. No statistically significant differences were found in clinical or medical history findings between patients with pathologic and nonpathologic GER.