Project Summary Endometriosis is a disease with a high prevalence that primarily affects women of childbearing age. This condition brings an important physical and emotional burden on sufferers and this is why it requires proper and timely medical management. At present there are several first-line drugs available for the management of symptoms and disease control. In the world literature we have reported several studies that demonstrate the effectiveness of different groups of drugs such as oral contraceptives, progestins, GnRH analogues and danazol. Within the available scientific evidence it has been extensively described the benefits of the new progestins Dienogest, demonstrating a favorable safety profile and efficacy along with a significant reduction of the symptoms of the disease by its anti-inflammatory, and antiproliferative antiagiogénicas in the endometrial tissue . However, although the therapeutic properties of this drug are known, studies are needed to compare its effectiveness with the effectiveness of other therapeutic agents as oral contraceptives. That is why the main objective of this study is to evaluate the impact of Dienogest to 2 mg / day compared with a combined oral contraceptive (levonorgestrel + ethinyl estradiol) in the size of the endometriomas diagnosed by transvaginal ultrasonography in 50 women having diameters less than 4 centimeters of the same, which medical management will be given for one year at the University Hospital Fundación Santa Fe de Bogota. The study was conducted by a clinical trial, randomized, single-blind by the observer. The results will be analyzed and the findings in the study will serve as a tool to define new therapeutic conduct in the management of endometriosis.