The mature cystic teratoma constitutes 20-30% of all the ovarian tumours. They are commonly seen in patients below the age of 20 years and are rarely seen in postmenopausal women. Here, we are reporting an unusual age presentation of mature cystic teratoma in a 70 year old postmenopausal female. She presented in the outpatient department with pain in lower abdomen for past 15 days. On bimanual pelvic examination, an abdominopelvic mass felt cystic in consistency, nontender in nature. MRI showed a large well defined Unilocular cystic abdominopelvic mass lesion measuring approximately 24 cm x 16cm x 9cm arising from the left ovary with multiple small cysts each measuring upto 14mm with provisional diagnosis ? cystadenoma left ovary. A total abdominal hysterectomy with left ovariectomy with b/l salpingectomy with right oophorectomy done. The histopathology report confirmed the large cyst as BENIGN CYSTIC TERATOMA. Although, the malignancy incidence is high in postmenopausal women but mature cystic teratomas can also have an unusual benign nature in postmenopausal age group as seen in our patient.