Ovarian epithelial dysplasia was initially described in material from prophylactic oophorectomies for BRCA mutation. Similar histopathological abnormalities have been revealed after ovulation stimulation. Given that tamoxifen (TAM) has a clomid-like effect and is sometimes used to induce ovulation, we studied the morphological features and immunohistochemical expression patterns of neoplasia-associated markers in adnexec-tomies previously exposed to TAM for breast cancer. We blindly reviewed 173 histopatholog-ical slides of adnexectomies according to three groups-oophorectomies associated with TAM exposure (n=42), oophorectomies associated with Clomiphene exposure (n=15) and a spontaneously fertile non cancerous control group (n=116). Morphological features (with an ovarian and tubal dysplasia scoring system) and immunohistochemical expression patterns of Ki-67, p53 and Aldehyde dehydroge-nase 1 (ALDH1 is an enzyme significantly associated with early-stage ovarian cancer) were evaluated and correlated. Mean tubal dys-plasia score was significantly higher in the TAM group and Clomiphen group than in controls (respectively 7.8 vs 3.5, P<0.007 and 6.8 vs 3.5, P=0.008). There is no statistical difference for the ovarian score in TAM group in comparison with the control group whereas we found a significant score for Clomiphen group (6.5, P=0.009). Increased ALDH1 expression was observed in the two exposed group whereas expression patterns of Ki67 and p53 were moderate. Interestingly, ALDH1 expression was low in non-dysplastic epithelium, high in dysplasia, and constantly low in the two carci-noma. Furthemore, we confirm our previous results showing that ALDH1may be a useful tissue biomarker in the subtle histopathologi-cal diagnosis of tubo-ovarian dysplasia.