The esophageal origin of angina-like noncardiac chest pain can be identified with certainty only when spontaneous chest pain episodes are associated with gastroesophageal reflux, abnormal esophageal motility, or both. Since noncardiac chest pain typically occurs infrequently, prolonged monitoring is required to establish such an association. Ambulatory esophageal monitoring offers the additional advantages of studying the patient in everyday life and avoiding hospital admission. Although the amplification and storage of 24-hour signals in a portable recorder no longer poses technical problems, the complexity of the analysis of the recorded signals should not be underestimated. For noncardiac chest pain, the most relevant part of the analysis is the association between chest pain episodes and the recorded esophageal signals. To determine whether contraction amplitude or duration during chest pain episodes is abnormal, their measurements are compared with baseline values from the same patient. Fully automated analysis by computer is feasible and, since it avoids observer bias, preferable. The yield of 24-hour monitoring in noncardiac chest pain reported by different groups of investigators varies considerably. Motor abnormalities have been identified as the cause of chest pain in 4.5-18% of patients studied, and reflux in 4.5-25%. In addition, some patients had both dysmotility- and reflux-related pain episodes. As expected, the yield of the technique is higher in patients with frequent pain episodes. In patients who do not experience pain during 24-hour monitoring, the technique cannot provide a firm diagnosis of pain of esophageal origin. Recently, a much higher yield of 24-hour monitoring was reported in patients with noncardiac chest pain admitted to a coronary-care unit. A total of 76% of these patients were found to have either reflux- or dysmotility-related chest pain. Despite its relatively low yield, the addition of esophageal pressure monitoring to ambulatory pH monitoring is worthwhile and probably also cost-effective in patients with frequent episodes of unexplained chest pain.