Strumaovarii, monodermal ovarian teratoma with incidence of 0.3%. Complications of struma ovarii includes torsion, rupture, infection and malignant transformation. We present you a unusual case of struma ovarii undergoing torsion without any clinical features of thyrotoxicosis in a 45year old postmenopausal women presented with lower abdominal pain and vomiting. Imaging study showed Right ovarian cyst and her thyroid function test, tumor markers(Ca-125, Ca 19-9) are within normal limits. It was histopathologically proven as Torsion struma ovarii. A solid cystic ovarian tumour diagnosed as Struma ovarii undergoing torsion as a complication.Even though struma ovarii is a rare ovarian tumor, we should keep in mind the complications which can happen with this type of tumor including the malignant transformations.