Objective: To assess the general population’s knowledge regarding the utility and availability of tools to diagnosis endometriosis, with focus on ultrasound. Design: An international cross-sectional online survey study was performed between August and October 2019. Setting and Population: 5301 respondents, representing 73 countries. Methods: 23 questions survey focused on knowledge of endometriosis diagnosis distributed globally via patient- and community-endometriosis groups using social media. Main outcomes and measures: Descriptive data of the knowledge of diagnostic tools for diagnosing endometriosis, including details about diagnosis using ultrasound. Results: 84.0% of respondents had been previously diagnosed with endometriosis, 71.5% of which were diagnosed at the time of surgery. Ultrasound and MRI were the methods of diagnosis in 6.5% and 1.8%, respectively. 91.8%, 28.8%, and 16.6% of respondents believed surgery, ultrasound and MRI could diagnose endometriosis, respectively (more than one answer allowed). In those diagnosed by surgery, 21.7% knew about ultrasound as a diagnosis method compared to 51.5% knowing in those diagnosed non-surgically (p<0.001). 14.7%, 31.1%, and 18.2% stated superficial, ovarian, and deep endometriosis could be diagnosed with ultrasound (32.9% stated they did not know which phenotypes of endometriosis could be diagnosed). 58.4% of respondents do not believe they could access an advanced ultrasound in their region. Conclusions: There are significant gaps in the understanding of diagnosing endometriosis using non-surgical tools in this study population.