Symptoms suggestive of gastro-oesophageal reflux disease are very common. The aim of the study was to assess the prevalence of these symptoms and factors influencing them in an unselected adult population. A questionnaire was mailed to a random sample of 2500 people aged > or = 20 years. The questions concerned heartburn, regurgitation, dysphagia, chest and upper abdominal pain, as well as medication and medical consultations for these symptoms. Of the 1700 (68%) responders, 9% had experienced heartburn on the day of response and 15%, 21% and 27% during the preceding week, month and year, respectively. The corresponding figures for regurgitation were 5, 15, 29 and 45%. During the past year 43% of the study group had had no such symptoms. Age, overweight, pregnancy and cigarette smoking significantly influenced the prevalence of symptoms. Using daily heartburn and/or regurgitation as dominant indicators 10.3% (95% CI 12-11.7) of the responders had gastro-oesophageal reflux disease. Medication (most commonly antacids) was used by only 16% of the symptomatic people, and only 5.5% had sought medical advice for symptoms during the past year. Thus, despite commonness of symptoms suggestive of gastro-oesophageal reflux disease only a minority of the individuals suffering from such symptoms use medication or have medical consultation.