Non-ulcer dyspepsia (NUD) is defined as dyspepsia in which investigation shows no evidence of focal gastroduodenal disease or oesophagitis. The aim of the present study was to determine the proportion of NUD patients with other identifiable diseases. We interviewed 327 consecutive patients who had at least 1 month of dyspepsia before a panendoscopy that showed no evidence of oesophagitis, malignancy, or peptic ulcer. Symptoms were assessed by a structured history questionnaire. The existence of gallstones was excluded radiologically. Of the subjects studied, 75 (23%) had irritable bowel syndrome and 71 (22%) gastro-oesophageal reflux, whereas 63 (19%) had both, 25 (8%) had aerophagy, and 14 (4%) had gallstones. Of the remaining 79 patients (24%) 6 had duodenitis and 10 gastritis, whereas 1 had both. Sixty-two subjects (19%) had entirely normal endoscopic results and no ascertainable cause of their dyspepsia (termed provisionally essential dyspepsia). It is concluded that, whereas three-quarters of NUD patients have diseases that fall into other diagnostic categories, nearly one-quarter have essential dyspepsia.