Women at high risk of ovarian cancer due to a genetic predisposition may opt for either surveillance or prophylactic bilateral salpingo-oophorectomy (pBSO). Main objective of our study was to determine the effectiveness of ovarian cancer screening in women with a BRCA1/2 mutation. We evaluated 241 consecutive women with a BRCA1 or BRCA2 mutation who were enrolled in the surveillance program for hereditary ovarian cancer from September 1995 until May 2006 at the University Medical Center Groningen (UMCG), The Netherlands. The ovarian cancer screening included annual pelvic examination, transvaginal ultrasound (TVU) and serum CA125 measurement. To evaluate the effectiveness of screening in diagnosing (early stage) ovarian cancer sensitivity, specificity, positive and negative predictive values (PPV and NPV) of pelvic examination, TVU and CA125 were calculated. Three ovarian cancers were detected during the surveillance period; 1 prevalent cancer, 1 interval cancer and 1 screen-detected cancer, all in an advanced stage (FIGO stage IIIc). A PPV of 20% was achieved for pelvic examination, 33% for TVU and 6% for CA125 estimation alone. The NPV were 99.4% for pelvic examination, 99.5% for TVU and 99.4% for CA125. All detected ovarian cancers were in an advanced stage, and sensitivities and positive predictive values of the screening modalities are low. Restricting the analyses to incident contacts that contained all 3 screening modalities did not substantially change the outcomes. Annual gynecological screening of women with a BRCA1/2 mutation to prevent advanced stage ovarian cancer is not effective.