Ovarian cancer is the most frequent cause of deaths from among gynecologic malignancies. Due to its asymptomatic development the disease is frequently diagnosed at an advanced, incurable stages. Although ovarian cancers usually respond well to the first line chemotherapy based on platinum compounds and taxanes, majority of patients develop recurrence and chemo-resistance. Despite many years of studies there is still lack of reliable diagnostic markers as well as other diagnostic methods enabling early detection and suitable for screening. Thus, current studies are aimed on finding new biomarkers with diagnostic, prognostic and predictive potential as well as on the search for the new therapeutic targets. Interestingly, an understanding of ovarian cancer etiology has changed fundamentally within recent years. The classical theory, claiming that ovarian cancers originate from ovarian surface epithelial cells, was undermined. Currently, there is a lot of evidence that majority of serous ovarian cancers have its origin in malignant tubal epithelium, while endometrioid and clear cell ovarian cancers develop most likely from endometriosis. These new findings will have an impact on diagnostic approaches as well as on the prevention options for women with genetic predisposition to ovarian cancer. The new knowledge about an origin of different histological types of ovarian cancer may open new pathways in basic research and clinical studies. In this paper we report current knowledge about ovarian cancer risk factors, we also present the arguments for extraovarian origin of the majority of ovarian cancers and stress the mechanisms of action of new drugs for targeted therapies that show most promising results in the current clinical trials.