Endometriosis generally causes pain that is cyclic and generally responds to medication and/or surgery. When endometriosis is found coincidentally, it may need no treatment because many women have endometriosis as a self-limited disease. In other women, the biologic behavior is much more unpredictable. Severe dysmenorrhea, focal pelvic tenderness, and deep dyspareunia are suggestive of endometriosis. Diagnosis at laparoscopy includes concerns about subtle appearance, endometriosis hidden within adhesions, retroperitoneal disease, and intra-ovarian lesions. Negative laparoscopy results do not mean that patients have no endometriosis. In contrast, a response to GnRH agonists can occur in patients with no endometriosis because conditions other than endometriosis are estrogen sensitive. Coexistent disease can confuse the picture at the time of surgery. Some coexistent diseases also can cause pain that is similar to that of endometriosis. Distinguishing those patients who need no treatment from those who need intermediate or extensive treatment can be very difficult. Care is needed to ensure that patients are neither overtreated or undertreated. An integrated approach involving a multidisciplinary team is needed in some. Other patients respond to primary care techniques.