Endometriosis is defined as the presence of endometrial tissue outside the uterus, which induces a chronic inflammatory reaction. It is an estrogen-dependent associated with pelvic pain and infertility. It is a relatively common chronic gynecological disease that affects approximately 10% of reproductive aged women. Patients with endometriosis often suffer from dysmenorrhea, dyspareunia, dysuria, and chronic abdominal or pelvic pain, resulting in a severely limited quality of life. The aim of most medical therapies is to alleviate the severity of symptoms. Commonly used hormonal therapies include combined oral contraceptives (OCP), progestogens, gonadotropin-releasing hormone (GnRH) agonists, androgens and antiprogestogens, all of which are considered to have similar efficacy but different tolerability profiles, which are often suboptimal. To date, the most widely used agent for the medical treatment of endometriosis is oral contraceptive (albeit off-label). In particular, evidence supporting the efficacy of estrogen-progestin therapy (EP) in pain control and reducing the risk of recurrence in women undergoing surgery for endometriosis. In recent years, the effectiveness of dienogest, a fourth-generation progestin, for endometriosis treatment has been demonstrated. Dienogest seems to be as effective as gonadotrophin-releasing hormone-a (GnRH-a) in terms of endometriosis-related pelvic pain improvement. The aim of this study is to evaluate the efficacy of Visanne versus OCP treatment of endometriosis associated pelvic pain in a double-blinded randomized controlled pilot study. It is a two armed pilot study; each group will include 50 patients. Women with endometriosis will be randomized to receive either DNG (n=50) or OCPs (n=50). The diagnosis of endometriosis will be by clinical evaluation, laparotomy, laparoscopy, or imaging analysis (combination of magnetic resonance imaging and ultrasonography) of endometriotic ovarian chocolate cysts.The first group will receive Deinogest (Visanne) 2mg/day, orally for 24 weeks. The second group will receive monophasic combined OCP (Yasmin, Ethinyl Estradiol and Drospirenone) daily for 24 weeks. The treating physician and the patients will be blinded to the treatment option. The relief of symptoms and efficacy will be evaluated by questionnaire on follow up visits at 3 and 6 month of the treatment. Data collected will be analyzed and compared between the 2 groups. We hypothesize that there will be no difference in pain scores, efficacy and safety between the two treatments.