The epidemiology and health-related quality of life associated with functional gastrointestinal disorders are reviewed, with particular emphasis on irritable bowel syndrome and functional dyspepsia. The literature supports the significant world-wide prevalence of functional gastrointestinal disorders, including irritable bowel syndrome (IBS), functional dyspepsia and chronic constipation. An increased female prevalence has been demonstrated in most studies in patients with IBS and chronic constipation, but not functional dyspepsia. The female to male ratio appears to be greater in the health care-seeking population than in community populations. However, some differences in the reported general prevalence and gender-related prevalence of functional gastrointestinal disorders may be due to cultural factors and study methodology. A significant health care burden is associated with IBS, with increased out-patient services, abdominal and pelvic surgeries, and gastrointestinal- and non-gastrointestinal-related physician visits and health care costs. Health-related quality of life is impacted significantly in patients with functional gastrointestinal disorders, such as functional dyspepsia and IBS, compared with the general healthy population, as well as patients with other chronic medical conditions, such as gastro-oesophageal reflux disease and asthma. Impaired health-related quality of life has been demonstrated, in particular, in patients with moderate to severe disease seen in referral settings. The health-related quality of life appears to improve in treatment responders, or correlates with symptom improvement, with at least some treatment modalities studied in functional gastrointestinal disorders, but further studies are needed. Predictors of health-related quality of life in patients with functional gastrointestinal disorders include psychosocial factors, such as early adverse life events, and symptoms related to visceral perception, e.g. pain and chronic stress. The presence of extra-intestinal symptoms appears to have a major if not greater impact on health care visits, excess health care costs and health-related quality of life in patients with functional gastrointestinal disorders.