PURPOSE: We estimate trends in the prevalence of urinary incontinence in the adult population of the United States from 2001 through 2008 before and after adjusting for other potential associated factors. MATERIALS AND METHODS: We analyzed data on 17,850 adults 20 years old or older who participated in the 2001 to 2008 cycles of the National Health and Nutrition Examination Survey. Any urinary incontinence was defined as a positive response to questions on urine leakage during physical activity, before reaching the toilet and during nonphysical activity. During this period changes in demographic and clinical factors associated with urinary incontinence included age, race/ethnicity, obesity, diabetes and chronic medical conditions (prostate disease in men). Age standardized prevalence estimates and prevalence ORs of urinary incontinence trends were determined using adjusted multivariate models with appropriate sampling weights. RESULTS: The age standardized prevalence of urinary incontinence in the combined surveys was 51.1% in women and 13.9% in men. Prevalence in women increased from 49.5% in 2001 to 2002, to 53.4% in 2007 to 2008 (Ptrend=0.01) and in men from 11.5% to 15.1%, respectively (Ptrend=0.01). In women increased prevalence was partially explained by differences in age, race/ethnicity, obesity, diabetes and select chronic diseases across the survey periods. After adjustment the prevalence OR for 2007 to 2008 vs 2001 to 2002 decreased from 1.22 (95% CI 1.03-1.45) to 1.16 (95% CI 0.99-1.37). In men adjustment for potentially associated factors did not explain the increasing prevalence of urinary incontinence. CONCLUSIONS: The age standardized prevalence of urinary incontinence increased in men and women from 2001 through 2008. Decreasing obesity and diabetes may lessen the burden of urinary incontinence, especially in women.