To study the pH monitoring over eight hours, analyzing variables such symptomatology and esophagogastroduodenoscopy, as well as the following pH monitoring parameters: number of reflux episodes, number of episodes longer than five minutes, length of reflux time during the eight hours, and the episode of longest duration, for the diagnosis of gastroesophageal reflux. A prospective study. Continuous measurement of esophageal pH was performed over eight hours on 35 patients whose ages ranged from four months to 11 years. The DPS-100 Diagnosis pH meter System was utilized, programmed in accordance with the methodology suggested by Vandenplas. The pH monitoring results were divided into positive and negative and compared with all the variables and parameters of the examination. We obtained statistically significant differences in all the pH monitoring parameters analyzed, with the reflux index being the most effective for identifying the pathological reflux, independent of age. None of the qualitative variables of age, symptomatology and esophagogastroduodenoscopy showed statistically significant differences when compared to the pH monitoring results. The esophageal pH monitoring of eight hours has its pH monitoring parameters validated for the diagnosis of gastroesophageal reflux.