Endometriosis is defined as the presence of the endometrium outside the endometrial cavity. If the ectopic mucosa is located within the endometrium, the disease is defined as endometriosis interna, or adenomyosis, whereas the localization of the endometrium outside the uterus is defined as endometriosis externa, or pelvic endometriosis. The diagnosis of pelvic endometriosis requires invasive techniques, such as laparoscopy or laparotomy, with histologic confirmation on the surgical specimen. The diagnosis of adenomyosis should be based on histology of hysterectomy specimen, since the endoscopic diagnosis is still too inaccurate. Laparoscopy allows the visualization of the different aspects of pelvic endometriosis, i.e. superficial implants, deep lesions, and associated adhesions. Staging is based on a score attributed to each location in order to establish a prognosis in terms of the patient's reproductive performance.