The ovarian masses are a common finding in the female population being a common reason for consultation in primary care, so it is very important to make an adequate approach to the adnexal masses always trying to catalog them according to their classification can be functional as cysts follicular and pathological such as neoplasms, whether benign, such as ovarian or malignant cystadenomas, such as cystadenocarcinomas.In the present case documentary review, we have presented the clinical case of a 24-year-old woman with a left adnexal mass corresponding to giant cystadenoma (37cm), which is defined as an ovarian cystic structure greater than 15cms (10) which in this particular case generates a compressive effect on the right ureter which leads to a right hydronephrosis, this being one of the most common complications in pelvic masses.