Introduction: Ovarian carcinoma accounts for one of the commonest malignant tumours among women worldwide. Their early diagnosis and management plays an important role in determining the prognosis. Several biomarkers for tumour antigen are used as important diagnostic tool. CA–125 is one such marker which is elevated in serum as well as expressed by tissue malignant cells. Two year study of all ovarian tumours was carried out along with tissue expression of ca–125 in malignant surface epithelial ovarian tumors. Results and observations: 32 cases of ovarian carcinoma were diagnosed histopathologically comprising of serous and mucinous type only. Ca–125 immunohistochemistry was done. 72.7% of serous carcinomas showed ca–125 positivity. None of the mucinous carcinomas were ca–125 positive. Conclusion : Though histopathology is the mainstay of diagnosis; immunohistochemistry can aid in certain doubtful cases as well to confirm ovarian origin