In order to evaluate the relationship between gastro-oesophageal acid reflux, as defined by pH recording, and clinical, endoscopic and histological findings, 43 patients with suspected gastro-oesophageal reflux (21 with typical and 16 with atypical symptoms) underwent endoscopy with biopsy and post-prandial oesophageal pH recording with a calculated acid reflux score. The history of each patient was carefully recorded. An acid reflux score higher than the mean +/- S.D. normal values was taken as diagnostic of gastro-oesophageal reflux. This level was reached in 30 out of the 43 patients. History taking gave 13 false-positive results (3 in the typical symptoms group, and 10 in the atypical symptoms group). The sensitivity and specificity of fiberoptic endoscopy as a means of diagnosing gastro-oesophageal reflux were 47% and 77% respectively. Histological data were available from only 77% of the patients; their diagnostic sensitivity and specificity values were 73% and 82% respectively. The absence of correlation between the intensity of the gastro-oesophageal reflux, as measured by pH recordings, and the severity of symptoms and endoscopic findings deserves to be noted.