Massive ovarian oedema (MOO) is a rare pseudotumour. It is often mistaken for a malignant tumour leading to radical treatment in young patients with the risk of compromising their fertility and hormonal function. Our article describes a case of MOO in a 29-year-old nulligravid patient, who presented with an acute abdomen evocative of an ovarian torsion. Ultrasonography revealed an enlargement of he left ovary measuring 75 mmx51 mm; partial resection of the ovary was performed by laparoscopy and MOO was diagnosed on histological examination. Torsion of the pedicle was not observed. In the event of ovarian hypertrophy, in a young woman with a symptomatic previous history, an exploratory laparoscopy should be undertaken to obtain biopsies for extemporaneous examination and detorsion of the ovary with suspension. Histology is the only means of obtaining a definitive diagnosis, thus preventing unnecessary oophorectomy.