Families with multiple cases of ovarian cancer have long been observed, and in the past prophylactic oophorectomy has been advocated for women with a history of ovarian cancer in two first-degree relatives. It is now thought that > 90% of familial ovarian cancer is due to inherited mutations in the BRCA1 breast-ovarian cancer susceptibility gene on chromosome 17q. BRCA1 testing is being performed in several academic medical centers on a research basis and is also now commercially available. With the ability to identify inherited mutations in BRCA1, prophylactic oophorectomy and other interventions intended to decrease cancer mortality can be offered specifically to women who carry a mutation, but the optimal strategy for decreasing cancer mortality in BRCA1 families has not yet been determined. To facilitate further clinical and basic research in this field, our group and others have established multidisciplinary hereditary breast-ovarian cancer clinics that offer a wide range of services including BRCA1 testing, genetic counseling, and cancer prevention and treatment.