This study assessed the probability that individuals tested for a BRCA1 gene mutation share their test results with family members, co-workers, and insurers. Members of a large kindred known to be at-risk for carrying a BRCA1 gene mutation were tested and they learned their results from a genetic counselor. During a follow-up interview, 4 months later, subjects were asked with whom they had shared their results. Respondents were most likely to have communicated results to family members, followed by co-workers, and insurers. Carrier status affected their willingness to disclose results to insurers. High rates of disclosure to family members should promote awareness of hereditary cancer risk. Selective disclosure to co-workers and insurers may promote information asymmetries that could affect employment and insurance markets.