The sensitivity of the string test for detection of gastroesophageal reflux was assessed in 15 infants and children, 5 months to 11 years of age (mean, 2.8 years), with vomiting, regurgitation, or lower respiratory tract symptoms, and compared with the barium esophagram, esophageal manometry, and the acid reflux test (pH probe). Barium esophagram showed reflux in 4/15 patients, pH probe in 7/15, and string test in 6/15. The string test is a simple, rapid, safe, and efficient screening method for patients with suspected gastroesophageal reflux.