Despite advances in medicine, ovarian cancer remains the deadliest of the gynecological malignancies. Herein we present the latest information on the pathophysiology of ovarian cancer and its significance for ovarian cancer screening and prevention. A new paradigm for ovarian cancer pathogenesis presupposes 2 distinct types of ovarian epithelial carcinoma with distinct molecular profiles: type I and type II carcinomas. Type I tumors include endometrioid, clear-cell carcinoma, and low-grade serous carcinoma and mostly arise via defined sequence either from endometriosis or from borderline serous tumors, mostly presenting in an early stage. More frequent type II carcinomas are usually high-grade serous tumors, and recent evidence suggests that the majority arise from the fimbriated end of the fallopian tube. Subsequently, high-grade serous carcinomas usually present at advanced stages, likely as a consequence of the rapid peritoneal seeding from the open ends of the fallopian tubes. On the other hand, careful clinical evaluation should be performed along with risk stratification and targeted treatment of women with premalignant conditions leading to type I cancers, most notably endometriosis and endometriomas. Although the chance of malignant transformation is low, an understanding of this link offers a possibility of prevention and early intervention. This new evidence explains difficulties in ovarian cancer screening and helps in forming new recommendations for ovarian cancer risk evaluation and prophylactic treatments.