Precancerous ovarian epithelial dysplasia was first described after prophylactic oophorectomy (OP) for genetic risk (BRCA mutation) or because of a strong family history of ovarian and/or breast cancer. The objective of this study was to describe histopathological features of ovarian dysplasia and to propose a dysplasia scoring sheme with a cut-off.One hundred and twenty-five bilateral oophorectomies (genetic predisposition: n=35 and control group: n=90) were reviewed by two pathologists blinded to clinical data. Eleven epithelial cytological and architectural features were studied and an ovarian dysplasia score was defined to compare the degree of ovarian epithelial abnormalities between the two groups.Mean ovarian dysplasia score was significantly higher in prophylactic oophorectomy group than in control group (9.0 versus 3.5, P<0.001). Dysplasia was more severe in OP with BRCA mutation than in OP without (11.6 in BRCA 1; 7.6 in BCRA 2; 7.1 in family history). The cut off for dysplasia was 8 with a sensitivity of 60% and a specificity of 93.3%.The increased dysplasia score in OP and the gradation in dysplastic severity in OP with proven BRCA mutations may suggest that ovarian dysplasia could be a pre-malignant non invasive histopathological lesion. The 11 cytological and architectural features in the dysplasia scoring sheme could be a useful tool to study ovarian dysplasia.