Sixty patients with anginalike chest pain of noncardiac origin were studied to determine the diagnostic value of 24-h ambulatory esophageal pH and pressure monitoring. The results of these 24-h studies were compared with those obtained by established methods, including x-rays, endoscopy with biopsy, conventional esophageal manometry, and acid perfusion test. Esophageal origin of the chest pain was considered to be likely if the familiar pain sensation was reproduced by the acid perfusion test, or if the pain occurred during an episode of gastroesophageal reflux, severe motor disorders, or both. When the results of established methods were combined and interpreted according to predetermined criteria, esophageal origin of the pain was shown to be likely in 27% of the patients. The 24-h recordings, alone, showed the esophagus to be the likely cause of the pain in 35% of the patients. Combination of all conventional examinations and of 24-h recordings made esophageal origin of the pain likely in 48% of the patients.