Dyspepsia refers to pain or discomfort centered in the upper abdomen. This symptom is remarkably common, with 1-year prevalence rates averaging 25% in the community. Symptoms suggestive of the irritable bowel syndrome and reflux disease frequently overlap but do not form part of the definition of dyspepsia. Electrical and other stimuli can cause similar or different symptoms in various patients, and even the site to which symptoms are referred varies considerably. Dyspeptic symptoms are therefore a relatively poor guide to the origin or nature of any "disturbances" in the gut. Identification of patients who require further investigation to rule out serious structural disease, such as peptic ulcer disease or cancer, is a key issue because unaided clinical diagnosis is unreliable. The use of an age threshold (typically 45 years) and the identification of alarm features, including weight loss, repeated vomiting, and signs of bleeding, seem to be valid on the basis of the limited evidence available. Dyspeptic symptoms fall into distinct subgroups resembling the perceived clinical entities of ulcer-like and dysmotility-like dyspepsia. Unfortunately, because of overlap with reflux symptoms and between the subgroups, the clinical significance of these groups remains highly questionable. A focus on symptom predominance may be more rewarding. Lack of validated outcome measures has hampered clinical studies and has led to the development of complex outcome measures that integrate and weigh different symptoms or other indirect indicators of outcome into a general score. Further testing and validation are in progress.