This study assessed the sociodemographic, medical and psychological predictors of accuracy of perceived risk in women at increased genetic risk for ovarian cancer. Women participating in a large cohort study who were at increased risk of ovarian and fallopian tube cancer, had no personal history of cancer and had ≥1 ovary in situ at cohort enrollment, were eligible. Women completed self-administered questionnaires and attended an interview at enrollment. Of 2,868 women unaffected with cancer at cohort enrollment, 561 were eligible. 335 women (59.8 %) overestimated their ovarian cancer risk, while 215 women (38.4 %) accurately estimated their risk, and 10 (1.8 %) underestimated it. Women who did not know their mutation status were more likely to overestimate their risk (OR 1.74, 95 % CI 1.10, 2.77, p = 0.018), as were those with higher cancer-specific anxiety (OR 1.05, 95 % CI 1.02, 1.08, p < 0.001) and/or a mother who had been diagnosed with ovarian cancer (OR 1.98, 95 % CI 1.23, 3.18, p = 0.005). Amongst the group of women who did not know their mutation status, 63.3 % overestimated their risk and the mean perceived lifetime risk of developing ovarian cancer was 42.1 %, compared to a mean objective risk of 6.4 %. A large number of women at increased risk for ovarian cancer overestimate their risk. This is of concern especially in women who are at moderately increased risk only; for this sub-group of women, interventions are needed to reduce potentially unnecessary psychological distress and minimise engagement in unnecessary surgery or screening.