Clear-cell carcinoma of the ovary (CCCO) is a distinct entity of epithelial ovarian cancer in terms of clinical, histopathological, or genetic features. The incidence of CCCO is different by ethnicity but the reason is not clear yet. Overall prognosis of CCCO is good because most CCCO is found in stage I. However, advanced disease is associated with a very poor prognosis and resistance to standard treatment. The same is true for recurrent disease. Therefore, genetic analysis of CCCO is important to find the right target(s) and better therapeutic approaches. Because of its rarity, international collaboration is necessary to conduct randomized clinical trials for CCCO.