Irritable bowel syndrome (IBS) is a long-term and episodic medical disorder shown to have an impact on work productivity and health-related quality of life (QOL). The objective of this study was to assess the impact of IBS on work productivity and on health-related QOL in an employed population in the United States and to quantify the cost of these factors to the employer. A 2-phase survey was sent to the workforce of a large US bank to assess the presence of IBS among employees and to measure their work productivity (absenteeism [time lost from work] and presenteeism [reduced productivity at work]) and health-related QOL. Forty-one percent of the 1776 employees responding to both phases of the survey met the Rome II criteria for IBS. Employees with IBS reported a 15% greater loss in work productivity because of gastrointestinal symptoms than employees without IBS and had significantly lower Medical Outcomes Study Short Form 36 (SF-36) scores than those without IBS. IBS was associated with a 21% reduction in work productivity, equivalent to working less than 4 days in a 5-day workweek. Employees with IBS also had significantly lower scores on all domains of the SF-36, indicating poorer functional outcomes. Reduced work productivity and diminished QOL of these magnitudes may have substantial financial impact on employers.