Background/Aims: To estimate the prevalence of diagnosed endometriosis (DE) in women in the United States and assess the associated symptomatic burden. Methods: An online, cross-sectional survey of women aged 18-49 years was conducted from August 6, 2012, through November 14, 2012. Survey data (weighted by age, race, education, income, geographical distribution, and propensity score) were used to estimate the prevalence and symptomatic burden of DE in women in the United States. Weighted logistic regressions were used to assess differences in symptom burden between women with and without endometriosis. Results: The prevalence of DE was estimated at 6.1% (2,922 of 48,020 women surveyed); 52.7% of women were 18-29 years of age when they were diagnosed with endometriosis. Most (86.2%) women experienced symptoms before diagnosis. More women with (vs. without) DE had menstrual pelvic pain/cramping (52.7 vs. 45.2%), non-menstrual pelvic pain/cramping (36.7 vs. 14.3%), infertility (11.6 vs. 3.4%), and dyspareunia (29.5 vs. 13.4%). Women with endometriosis were also more likely to report severe symptoms (OR (95% CI) 2.7 (2.3-3.1) for menstrual pelvic pain/cramping, 2.2 (1.7-2.9) for non-menstrual pelvic pain/cramping, and 2.4 (1.8-3.2) for dyspareunia). Conclusion: The prevalence of DE among US women is notable, and affected women experience a substantial symptom burden.