This article describes breast or ovarian cancer surveillance practices and prophylactic surgery involving 34 carriers and 34 noncarriers of a BRCA1/2 mutation within the year after predictive testing. It also evaluates the effect of the predictive test result on cancer screening practices and provides insight into factors important in the decision-making process about health-related behavior. Within the year following predictive testing, 9% (3 of 34) of the carriers decided to have a prophylactic mastectomy. The majority of the carriers was adherent to recommendations regarding regular cancer surveillance following predictive testing. Furthermore, carriers' adherence to clinical breast examination and mammography recommendations significantly increased from pre- to posttest and was significantly higher than noncarriers' utilization after testing. Of the carriers eligible for prophylactic salpingo-oophorectomy, 75% had this operation. All carriers who were advised to have regular surveillance of the ovaries had ovarian ultrasounds. The authors gave major attention to factors playing a part in the decision-making process about health-related behavior.