Limited attention has been given to the impact of BRCA mutation disclosure on participants' psychological reaction and cancer control compliance. We asked women (290 mutation-positive, 370 mutation-negative) from 84 hereditary breast-ovarian cancer (HBOC) families with known deleterious BRCA mutations to participate in an evaluation regarding cancer prevention recommendations before and after BRCA mutation disclosure. Both men and women (n = 780) were invited to complete a questionnaire to evaluate their psychological response to BRCA mutation disclosure. Before BRCA testing, 23.0% (152 of 660) of these women underwent prophylactic bilateral mastectomy, oophorectomy, or both; of these, 53% (80 of 152) were subsequently found to be mutation negative. After mutation disclosure, 52.9% (110 of 208) of mutation carriers and 0% (0 of 203) of noncarriers underwent prophylactic surgeries. These changes were statistically significant compared with before disclosure (P < 0.0001). The rate of transvaginal ovarian ultrasound screening was significantly increased in mutation carriers (P < 0.015) and marginally decreased in noncarriers (P = 0.063) post disclosure. Psychologically, compared with noncarriers without cancer, a significantly higher percentage of carriers, regardless of their cancer status, felt guilt about passing a mutation to their children, worried about developing additional cancer or their children developing cancer, and were concerned about health insurance discrimination. Despite these psychological consequences, carriers and noncarriers reported a positive attitude toward genetic testing.