Gastro-esophageal reflux (GER) in infants was studied using 24-hour esophageal pH monitoring. Gastro-esophageal reflux was detected in 32/41 subjects. In our patients the main symptoms were vomiting, regurgitation, failure-to-thrive, chronic respiratory problems such as asthma, apnea, recurrent pneumonia. All patients with GER were treated appropriately with prone positioning and medical therapy (prokinetic agent and, eventually, ranitidine). Successful treatment of the reflux was obtained in all patients. In our opinion the 24-hour intraesophageal pH monitoring is a highly diagnostic test to identify the presence of GER and evaluate its gravity.