Approximately 5 to 10 % of all ovarian cancers arise in the setting of a major genetic predisposition. The two main hereditary forms of ovarian adenocarcinomas are the hereditary breast/ovarian cancers associated with a BRCA1 or BRCA2 gene mutation and the Lynch syndrome associated with a MLH1, MSH2, MSH6 or PMS2 gene mutation. Their identification and the characterization of a causative germline mutation are crucial and have a major impact for affected women and their relatives in terms of medical management. The aim of this review is to indicate cancer risks associated with these two entities, to evaluate their contribution in the pathogenesis of ovarian cancers and to indicate the clinical data suggestive of these diagnoses, the validated indications for genetic analyses and the current management guidelines. We will also illustrate the diagnostic strategy by reporting a clinical observation.