Background & Objective: The aim of this study was to determine the endometriosis-associated symptoms and diagnostic delay through an online survey. Materials & Methods: A cross-sectional study was conducted in Australia using an online web-based survey. All data were entered into and analyzed using the STATA software (version 14.1). A total of 903 respondents completed an online survey from September 2013 to October 2015. Results: Out of 903, 71.10% were Australians and 28.90% were Non-Australian, with a self-reported diagnosis of endometriosis confirmed by surgery. Out of the participants, 86.5% completed the online survey. Delay in diagnosis was 8.1±6.2 years. There was no difference in the age range (P = 0.35), mean age of onset of the first symptoms (P = 0.93), and delay in diagnosis (P = 0.11) between both groups. Most common endometriosis-related symptoms that all respondents had experienced in their lifetime were period pain (98.1%), fatigue (94%), bloating (90.7%), ovulation pain (88.7%), pelvic pain (87.3%), pain during and before/after sexual activity (82.7%), and heavy bleeding (82.2%) .Treatments used by affected women included: pain killers (96%), hormonal medication (84.7%), surgical treatments (84.5%), and delayed fertility (37.1%). Conclusion: Vast similarities in demographics and endometriosis-associated symptoms among the Australian and non-Australian women with endometriosis support the universality of the disease characteristics. Delay in diagnosis of endometriosis is a problem and the reasons for delayed diagnosis must be understood to try to shorten this delay. Besides pain, patients with endometriosis suffer from a variety of other symptoms; hence, any treatment must take into account the most prominent symptoms.