PURPOSE: This study was designed to estimate the prevalence of, and identify risk factors associated with, fecal incontinence in racially diverse females older than aged 40 years. METHODS: The Reproductive Risks for Incontinence Study at Kaiser is a population-based study of 2,109 randomly selected middle-aged and older females (average age, 56 years). Fecal incontinence, determined by self-report, was categorized by frequency. Females reported the level of bother of fecal incontinence and their general quality of life. Potential risk factors were assessed by self-report, interview, physical examination, and record review. Multivariate logistic regression analysis was used to determine the independent association between selected risk factors and the primary outcome of any reported fecal incontinence in the past year. RESULTS: Fecal incontinence in the past year was reported by 24 percent of females (3.4 percent monthly, 1.9 percent weekly, and 0.2 percent daily). Greater frequency of fecal incontinence was associated with decreased quality of life (Medical Outcome Short Form-36 Mental Component Scale score, P = 0.01), and increased bother (P < 0.001) with 45 percent of females with fecal incontinence in the past year and 100 percent of females with daily fecal incontinence reporting moderate or great bother. In multivariate analysis, the prevalence of fecal incontinence in the past year increased significantly [odds ratio per 5 kg/m2 (95 percent confidence interval)] with obesity [1.2 (1.1-1.3)], chronic obstructive pulmonary disease [1.9 (1.3-2.9)], irritable bowel syndrome [2.4 (1.7-3.4)], urinary incontinence [2.1 (1.7-2.6)], and colectomy [1.9 (1.1-3.1)]. Latina females were less likely to report fecal incontinence than white females [0.6 (0.4-0.9)]. CONCLUSIONS: Fecal incontinence, a common problem for females, is associated with substantial adverse affects on quality of life. Several of the identified risk factors are preventable or modifiable, and may direct future research in fecal incontinence therapy.