Atypical endometriosis is considered to be precursors for malignancy. Coexistence of atypical endometriosis and ovarian neoplasm has been found in some studies. We describe the case of a 48-year old women diagnosed with clear cell carcinoma of ovary. The review of histological slide confirms the presence of benign endometriosis in both ovaries, the atypical endometriosis and clear cell carcinoma in the right ovary and the presence of uterine leiomyoma.