Quality-of-life (QOL) assessment is becoming increasingly important in the evaluation of the impact of disease and the effect of therapy. This is particularly so forirritable bowel syndrome (IBS) where there is often a tendency for a chronic clinical course, but with no associated mortality. Instruments used to study quality of life may be generic or disease specific, and care needs to be taken to ensure that the instrument used has been adequately validated for the purpose intended. Several disease-specific instruments [Irritable Bowel Syndrome Quality of Life (IBS-QOL, IBSQOL) and Functional Digestive Disorders Quality of Life (FDDQL)], in addition to generic measures, are now available for use in IBS. Quality of life in patients with IBS is surprisingly poor, particularly in the population seeking healthcare, where it can be compared with conditions which carry a high mortality, such as ischaemic heart disease, heart failure and diabetes mellitus. Pain severity appears to be an important factor in determining quality of life in IBS, although bowel disturbance and psychological difficulties are also likely to be important. There is limited data on the effect of treatment of IBS on quality of life. Improvement has been reported with dietry modification, drug treatments and hypnotherapy. It is likely that, in the future, QOL measures will become increasingly used as secondary end-points in therapeutic trials in IBS.