A 15 years old young girl with short stature presented with huge distension of abdomen of 2 months duration. She was not able to eat properly and was also having urinary and fecal incontinence. The abdomen was so grossly distended that she was having difficulty in breathing too. CT scan of the abdomen showed a huge multiseptated cystic mass in the abdomen which was occupying the entire abdomen, it had pushed the diaphragm above and was interfering with breathing, it had compressed the stomach resulting in vomiting and loss of appetite, it had also grossly compressed the bladder and rectum resulting in fecal and urinary incontinence. Organ of origin could not be established on CT as the mass was occupying the entire abdominal cavity along with the pelvis so differential diagnosis of Mesenteric Cyst, Omental Cyst and Ovarian Cyst were given. After thorough planning the patient was taken for surgery, intraoperatively, the mass turned out to be a large ovarian cyst and was removed completely. The weight of the excised mass was about 6.5 kg and the size was about 18 inches along the longer axis. The weight of the child preoperatively was 30 kg and postoperatively at the time of discharge she weighed only 23 kg. All the symptoms of the girl had resolved postoperatively.