Abstract: Parovaraian cysts are simple cysts arising from the adnexa occurring most commonly in the women of reproductive age group. Rarely can they be of neoplastic origin. Female of 21 years presented with pain in abdomen. On basis of clinical examination, ultrasonography and biochemical tumour markers it was diagnosed as ovarian tumour. At laparotomy it was seen to be parovarian cyst of 12cm x 14cm size. On histopathology it was proved to be a neoplastic parovarian cyst - serous cystadenoma.