Approximately 5% of ovarian cancer cases can be attributed to an autosomal dominant inheritance factor. The majority of these cases are due to germline mutations in the BRCA1 or BRCA2 tumoursupressor genes. Patients with hereditary disease do not exhibit pathognomonic features that would allow distinction from non-hereditary (sporadic) cases of ovarian cancer. Our studies are aimed at identifying clinical, histopathological as well as molecular genetic differences between hereditary and sporadic ovarian cancer. Clinical studies of the ovarian cancer cases in 31 families revealed differences regarding age at onset and stage as well as in survival compared with cancer registry controls. The molecular studies of hereditary ovarian cancer are still underway and some preliminary data is discussed.