The objective of this study was to compare the estrogenicity of xenoestrogens found in food wrap packaging and phytoestrogen flavonoids. Uterotrophic and vaginal cornification assays were performed on immature and ovariectomized rats. Genistein, bisphenol F, and octylphenol were identified as estrogenic only in immature rats. Using vaginal cornification as a more specific estrogenic parameter, all tested compounds except tangeretin were active in immature rats. While apigenin and kaempferol appeared to have low estrogenic activity, they potentialized the uterotrophic effect of 17β-estradiol in immature rats. These data showed that (i) phytoestrogens like genistein can be as potent or even more estrogenic than compounds found in food wrap packaging, (ii) immature rats appear to be a more sensitive in vivo model than ovariectomized rats in term of estrogenicity, (iii) the vaginal cornification assay could be a sensitive and useful test to detect weak estrogenic compounds to which humans can be exposed via food.