In this study, we found that abundant expression of MDM2 was significantly associated with poor prognosis (PFS and OS) in ovarian clear cell carcinomas, and that the MDM2 inhibitor RG7112 has in vitro and in vivo antitumor and proapoptotic activities in clear cell carcinomas without TP53 mutations. The gene discussed is MDM2; the disease is ovarian clear cell cancer.