Malignant struma ovarii is a very rare disease. Only few cases are reported in literature. Because of its rarity, there are various approaches to its treatment. We describe a case of malignant struma ovarii, in a 37 year-old female who presented for non cyclic, chronic pelvic pain and the presence of a right ovarian cyst with mean diameter of 7 cm. The patient was treated with laparoscopic right ovariectomy and with multiple biopsies of omental, left ovary and utero-sacral ligament. The patient underwent subsequently total thyroidectomy and radioiodine (131I) ablation. A Medline literature search was performed; we found 48 cases of malignant struma ovarii. The therapeutic management of the disease is very different in the described case; particularly after surgical removing of the ovarian mass, the treatment is still controversial. We think that the management of malignant struma ovarii could be the same than carcinoma of the thyroid, so after surgical removing of ovarian neoplasm, we recommend thyroidectomy, radiotherapy with 131I and levothyroxine suppressive therapy.