In anticipation of the identification of the BRCA1 gene, we studied the interest in and anticipated reaction to DNA testing for mutations in this gene in members of high-risk families. We surveyed 91 female and 49 male subjects using a structured interview by study nurses. All subjects were members of inherited breast-ovarian cancer families participating in a genetic linkage study at the National Cancer Institute. The main outcomes of the study were interest in genetic testing and anticipated impact of test results. Seventy nine % of subjects indicated that they would "definitely" want to be tested, and 16% would "probably" want to be tested for mutations in the BRCA1 gene. Subjects with a high self-perceived risk of having an altered BRCA1 gene were more likely to definitely want testing (P = 0.02), while estimated true genetic risk did not predict interest in the test. Females were significantly more likely to definitely want testing (P = 0.005) and had a significantly greater mean anticipated negative-impact score (2.3) compared to males (1.0) (P < 0.001). We found a high level of interest in genetic testing for BRCA1 among members of inherited breast-ovarian cancer families participating in a genetic linkage study. While utilization may fall below levels of interest reported in this and other preliminary surveys, given the potential for early detection and treatment of breast and ovarian cancer, interest in BRCA1 testing may translate into high rates of uptake. These results indicate that it will be critical to incorporate follow-up counseling and support into BRCA1 testing programs.