BackgroundFecal incontinence (FI) is a prevalent but poorly recognized problem in the general population with profound negative effects on daily life. The prevalence of FI in irritable bowel syndrome (IBS) and its association with clinical, demographic, and pathophysiological factors remain largely unknown. MethodsOne US (n=304) and one Swedish (n=168) patient cohort fulfilling Rome III criteria for IBS completed Rome III diagnostic questions on FI and IBS symptoms, and questionnaires on IBS symptom severity, quality of life, anxiety and depression, and work productivity impairment. The patients also underwent assessments of colorectal sensitivity and motility. Key ResultsFecal incontinence one day per month was reported by 19.7% (USA) and 13.7% (Sweden) of IBS patients. These proportions rose to 43.4% and 29.8% if patients with less frequent FI were included. Fecal incontinence prevalence was higher in older age groups, with a clear increase above age 40. Irritable bowel syndrome patients with FI reported greater overall IBS symptom severity, more frequent and loose stools, and greater urgency. Negative effects of FI on quality of life, psychological distress, and work productivity were demonstrated. No associations were found between colorectal physiology and FI. Conclusions & InferencesFecal incontinence is common in IBS patients, and similar to previous general population reports, the major risk factors for FI in IBS are older age, rectal urgency, and loose, frequent stools. When IBS patients have comorbid FI, the impact on quality of life, psychological symptoms, and work impairment appears greater.