Esophageal 24-h pH monitoring: is prior manometry necessary for correct positioning of the electrode? In 24-h esophageal pH monitoring, the electrode is usually positioned 5 cm above the manometrically localized esophagogastric junction. In order to replace esophageal manometry for this purpose, we tested whether the esophagogastric junction can be identified correctly by fluoroscopy or the determination of the pH-step between stomach and esophagus, compared with esophageal manometry. The distance from the nares to the esophagogastric junction was determined three times with each of the three methods in 46 patients and 14 volunteers. Fluoroscopy assumed the esophagogastric junction 1.23 +/- 0.23 cm (mean +/- SE) lower than the peak pressure point determined at manometry, pH-step only 0.45 +/- 0.16 cm. With pH-step, only one subject had a difference of more than 3 cm to the manometrically defined esophagogastric junction, whether gastroesophageal reflux disease (as proven by pH monitoring) was present or not. We conclude that the esophagogastric junction can usually be identified with sufficient accuracy by the measurement of the pH-step between stomach and esophagus. Fluoroscopy is far less accurate than pH-step, and should not be used. 