The frequency of different kinds of oesophageal dysfunction (OD) as shown by manometry and acid perfusion test was investigated in a 55-year-old general population. OD was found in 34 +/- 8% (95% confidence interval). Seventeen per cent had signs of dysmotility, 14% of hiatal hernia, 6% of lower oesophageal sphincter (LES) hypotension, 5% had a positive acid perfusion test and 13% had more than one kind of OD. Symptoms of gastro-oesophageal reflux and chest symptoms were significantly more common in OD subjects than in subjects with normal oesophageal function. The oesophageal function tests had a capability in detecting 66% of subjects in the general population with heartburn or acid regurgitation, whereas they had a poor capability in detecting subjects with other oesophageal related symptoms. This investigation can therefore not answer the question whether our criteria for OD is clinically relevant or not. Irrespective of this, it is important to know the frequency of OD in the general population if the relevance of the OD frequency in hospital patient materials is to be evaluated.