The cumulative lifetime risk of developing breast cancer for a Dutch woman is about 12%. In some families breast cancer seems to occur even more frequently or women fall ill at a relatively young... Show moreThe cumulative lifetime risk of developing breast cancer for a Dutch woman is about 12%. In some families breast cancer seems to occur even more frequently or women fall ill at a relatively young age. Such families may have a genetic susceptibility towards breast cancer. To learn more about the likelihood of this susceptibility actually being present, members of such families may request genetic counselling and DNA-testing. The main purpose of this thesis is to provide more insight into some effects of genetic counselling and DNA testing for breast cancer. We address effects on: (a) risk perception; (b) psychological distress; and (c) intentions for risk-management behaviour. Regarding the effects of DNA testing, special attention is paid to women who receive a so-called uninformative DNA-test result. The data of this thesis do not provide support for one of the two hypotheses which has been postulated about the impact of an uninformative result. They suggest that, as a group, women seem to be reassured upon learning their uninformative result, but to a lesser extent than women who received a true negative result. Only a small minority of women with an uninformative result incorrectly concluded that the chance of a mutation being present was non-existent. Show less