The aim of this study was to examine the patterns of disclosure of BRCA1/2 genetic test results to employers by unaffected carriers. In a national prospective cohort study on unaffected BRCA1/2 mutation carriers, disclosure to employers was assessed prospectively, using self-administered questionnaires, up to 2 years after their test results were delivered by cancer geneticists. Kaplan-Meier curves and Cox-regression analysis were used to assess the factors associated with time to disclosure to the employer. Mean age of the 146 women BRCA1/2 carriers who were employed when their test results were delivered was 37.1 years (range: 19-57). At the end of the second year of follow-up, 47 of them (32.2%) had disclosed their results to their employers; median time to disclosure was 6 months. Reasons spontaneously expressed were first to inform the employer that medical surveillance/surgery was necessary for cancer risk management although these carriers did not actually have cancer. After multivariate adjustment on age, women with a lower educational level (HRadj=2.00, P=0.026) and those who had undergone prophylactic surgery during the 2 years of follow-up (HRadj=2.18, P=0.019) had disclosed their BRCA status to their employers earlier and more frequently. One-third of the female carriers not affected by breast/ovarian cancer disclosed their BRCA1/2 genetic test results spontaneously to their employers, mainly to inform them that they were disease-free but required medical surveillance or a surgical intervention to reduce the risk of cancer.