One of the most characteristic features of epithelial ovarian cancer is its inherent heterogeneity with respect to biological behavior ranging from the relatively indolent nature of borderline tumors to highly aggressive malignant diseases. This can be reflected in a wide variety of prognostic factors, among which the stage of disease is by far the most important, followed by histologic subtype, histologic grade, volume of residual disease, age at diagnosis, and performance status (PS). Within a given stage, histologic grade is the most powerful prognostic factor in stage I disease, followed by dense adherence and large volume of ascites. On the other hand, the main prognostic factor in more advanced stage disease (II-IV) includes an effect of chemotherapy and a volume of residuum, and PS. However, these factors alone cannot always predict patients' survival correctly. A number of new and potentially valuable prognostic factors have emerged as a result of the recent technical advances in molecular genetics, flow cytometric analysis, development of monoclonal antibody, immunohistochemical study, and steroid hormone receptor analysis. This article reviews some of these newly developed "investigational" prognostic variables, as well as the "widely accepted" clinicopathological prognostic factors.