Ovarian cystic endometriosis, endometrioma, may present on ultrasonography as an easily identifiable hyper-refringent adnexal mass and the most frequent variation. Different studies have tried to evaluate the diagnostic capacity of transvaginal sonography (TVS) in deep endometriosis. When ultrasonographic findings were compared with surgical findings and pathology reports, a low sensitivity (around 30%) was reported for vaginal or rectovaginal septum endometriosis, with a high rate of false negatives. Infertile women with endometriosis have a higher prevalence of associated functional images, such as unruptured luteinized follicles, hydrosalpinges, adenomyosis, and/or intraovarian endometriosis that may interfere with oocyte retrieval. The role of TVS in the diagnosis of extraovarian endometriosis, an area where magnetic resonance imaging (MRI) has proved to be much more beneficial, is yet to be established. MRI offers a better suggestive diagnosis of adenomyosis than TVS due to its lower interobserver variability.