Background: To our knowledge, the burden of disease attributed to erectile dysfunction (ED) has not been adequately quantified across a complete spectrum of age and race using a global disease definition, as recommended by the National Institutes of Health consensus statement. To obtain a better understanding of the national estimates of prevalence and risk factors for ED, we analyzed data from the 2001-2002 National Health and Nutrition Examination Survey. Methods: The National Health and Nutrition Examination Survey collects data by household interview. The sample design is a stratified, multistage, probability sample of clusters of persons representing the civilian noninstitutionalized population. Data include medical histories in which specific queries are made regarding urological symptoms (including ED). These items were selected for analysis in 3566 men, 20 years and older. Results: In men 20 years and older, ED affected almost 1 in 5 respondents. Hispanic men were more likely to report ED (odds ratio [OR], 1.89), after controlling for other factors. The prevalence of ED increased dramatically with advanced age; 77.5% of men 75 years and older were affected. In addition, there were several modifiable risk factors that were independently associated with ED, including diabetes mellitus (OR, 2.69), obesity (OR, 1.60), current smoking (OR, 1.74), and hypertension (OR, 1.56). Conclusions: The burden of ED on the US population is significant. Hispanic men had an elevated risk for ED, a finding that requires confirmation in prospective studies. Obesity, hypertension, smoking, and diabetes mellitus are significantly associated with ED risk. Mitigation of these risk factors may ameliorate the burden of ED.