To study the prevalence of dyspepsia in the community a postal questionnaire was sent to 2697 patients who were selected at random from the lists of patients registered in two health centres in Hampshire. A total of 2066 returned questionnaires were suitable for analysis (response rate 77%). It was found that the six month prevalence of dyspepsia was 38%. There was considerable overlap between symptoms of heartburn and upper abdominal pain, with over half of patients with dyspepsia experiencing both. One in four of these patients had consulted their general practitioner during that time. The proportion of patients with dyspepsia who consulted their general practitioner varied widely among the eight doctors who participated in the study, from 17% to 45%. Frequency of symptoms tended to fall with age, particularly in men, while the proportion of patients with dyspepsia who sought medical advice increased with age. Almost one in five of the 2066 patients had been investigated with radiology or endoscopy at some time, and 143 (7%) of them claimed to have had a diagnosis of peptic ulcer.