It is often recommended that women who carry a mutation in the BRCA1 or BRCA2 gene have their ovaries and fallopian tubes removed to reduce their risk of gynecologic cancer. The aim of this study was to evaluate women's perception of their risk of breast and ovarian cancer before and after prophylactic salpingo-oophorectomy. We surveyed 127 women who carry a BRCA1 or BRCA2 mutation and who underwent prophylactic salpingo-oophorectomy at the University Health Network, Toronto. Subjects were asked to estimate their risks of breast and ovarian cancer before and after surgery. Their perceived risks of cancers were then compared with published risks, based on their mutation status. BRCA1 carriers estimated their risk of breast cancer risk to be, on average, 69% before surgery and 41% after surgery. They estimated their risk of ovarian cancer to be 55% before surgery and 11% after surgery. BRCA2 carriers estimated their risk of breast cancer to be 69% prior to surgery and 45% after surgery and their perceived risk of ovarian cancer to be 43% before surgery and 8% after surgery. Compared with published risk figures, the perceived risk of ovarian cancer before prophylactic salpingo-oophorectomy was overestimated by 47% of BRCA1 mutation carriers and by 61% of BRCA2 mutation carriers. Most women who have undergone genetic counseling and subsequently choose prophylactic salpingo-oophorectomy accurately perceive their risk of breast cancer. However, in this study, many women overestimated their risk of ovarian cancer, particularly women who carry a BRCA2 mutation.