Endometriosis is a common cause of infertility and disabling pelvic pain in reproductive age women. The most widely accepted theory of its pathogenesis is the retrograde flow of menstrual products, although extra-abdominal and extrapelvic diagnoses have been made. After the pelvic peritoneum and gynecologic structures, the most commonly affected sites are the lower gastrointestinal and urinary tracts. When the urinary tract is involved, the bladder is the predominant site, followed by the ureters. The focus of this seminar will thus be these two anatomic sites. Delayed diagnosis is unfortunately common for endometriosis as a whole, but more so when extrapelvic sites are involved. While the first-line therapy for endometriosis is medical management, urinary tract involvement often represents advanced stage of the disease, thereby requiring surgical intervention. With timely diagnosis and intervention by skilled gynecologic or urologic surgeons, favorable outcomes can be attained.