The child's discomfort and the cost of overnight hospitalization are clear disadvantages of prolonged esophageal pH monitoring. The aim of this study was to verify the reliability of short recording versus 24-h testing in a pediatric series with symptoms suggestive of gastroesophageal reflux (GER) disease. A 24-h pH monitoring performed on 160 patients with either gastroenterological symptoms (n = 61), respiratory problems (n = 58), or emesis plus respiratory problems (n = 41) was reviewed. Regardless of clinical presentation, children were also classified according to age: < 12 months (n = 39), 12-71 months (n = 81), and 72-168 months (n = 40). A diurnal fraction of 6 h, including at least 2 h after a meal, was compared to the entire 24-h recording in all groups with respect to the reflux index (RI) (sum of the periods with pH < 3.9 expressed as percentage of time) and reflux/h. RIs of > 10% were considered positive in patients < 1 year of age, whereas RIs of > 5% were considered positive in other age groups. Negative predictive values of the short recording RI ranged from 71 to 90%. Positive predictive values ranged from 50 to 83%; it was unreliable for children < 12 mos (50%) and patients with emesis plus respiratory problems (64%), who were, significantly, the youngest. Reflux/h values were not in agreement for the same groups. Absence of agreement was found if the absolute value of RI was considered.(ABSTRACT TRUNCATED AT 250 WORDS)