Endometriosis is a chronic inflammatory gynecological disorder associated with pelvic pain symptoms and infertility. Ovarian cysts (endometriomas) are the most common localization of endometriosis in the pelvis. Considering non-invasive methods, transvaginal ultrasound has high sensitivity and specificity for endometrioma diagnosis. Laparoscopic removal of endometrioma is related to a damage to the ovarian reserve and should be limited to patients with suspicious cysts or unresponsive to medical treatment. The main goal of medical therapy of symptomatic endometrioma is the control of pain symptoms, while no benefits have been demonstrated in terms of improving fertility rates of women seeking pregnancy. The aim of medical treatment is the inhibition of ovulation, stop of menstruation and achievement of a stable hypo-hormonal milieu. Estroprogestins and progestins are indicated by guidelines as first line medications for symptomatic patients. Several hormonal treatments have been proposed for the treatment of symptomatic endometriomas. In particular, dienogest, a relatively new progestin, has shown promising results. Medical treatment should be conceived as a long-term treatment. Safety, tolerability, a low percentage of side effects and an easy route of administration are essential for patient acceptance and adherence to therapy.