Objectives: To identify the impact of irritable bowel syndrome (IBS) on health-related quality of life (HR-QOL), time off work and the utilisation and cost of health services., Design: A case-control study was undertaken matching patients with IBS and controls. Quality-of-life information was collected using the Medical Outcomes Study 36-item Short Form (SF-36) health survey, EuroQOL instrument (EQ-5D) and IBS Quality-of-Life (IBS-QOL) instruments. Data on time off work was also collected. National Health Service (NHS) resource use in primary and secondary care was estimated by review of general practitioner (GP) and hospital records over a 12-month period., Setting: Recruitment was from six GPs' surgeries in the Trent Region of the United Kingdom., Participants: 161 patients with IBS, as defined by the Rome Criteria I were recruited. These were compared with 213 controls matched for age, sex and social characteristics., Main Outcome Measures: SF-36 and EQ-5D scores; mean number of days off work; mean NHS costs per person during the 12-month study period., Results: Patients with IBS had considerably lower HR-QOL than controls. They scored worse in all dimensions of the SF-36 and the EQ-5D and they had more time off work. On average patients with IBS cost the NHS 123 UK pounds (95% confidence interval: 35 UK pounds to 221 UK pounds, 1999 values) more per year than individuals in the control group (p = 0.04)., Conclusions: IBS affects patients through reduced quality of life, more time off work and greater healthcare utilisation than a control group of patients without IBS. The difference in quality of life was pronounced and unusual in that it was influential in every dimension of both the SF-36 and the EQ-5D.