In a series of 18 patients with angina pectoris, in whom treatment over at least 3 years with nitroderivatives and Ca-antagonists had become partially ineffective on chest pain, and in 18 patients with angina-like non-cardiac chest pain, the following examinations were carried out: upper gut x-ray and endoscopy, acid perfusion test, esophageal manometry, 24-hour esophageal pH monitoring associated with Holter recording. The presence or absence of coronary insufficiency was established by means of scintigraphic and ECG tests, Holter monitoring and coronary arteriography. In both groups the majority of patients had abnormal esophageal function, but in patients with angina pectoris treated for a long period of time the motility changes were prevalently reflux-related. With respect to the origin of chest pain, the esophagus was found to be the likely cause in 4 patients with angina pectoris, and the probable cause in another 10 of the same group; it was the likely cause in 7 patients without angina pectoris, and the probable cause in another 7 of the same group. As nitroderivatives and Ca-antagonists decrease the LES tone and the amplitude of esophageal pressure waves, long-term treatment with these drugs may be taken into account in the genesis of gastro-esophageal reflux and related changes, including esophageal pain.