Hormonal compounds are a class of pharmaceutical product that disrupt the endocrine system of animals and humans. Exposure to these molecules, even at low concentrations, can have severely damaging effects on the environment, to organisms, and to humans. The cumulative presence of these compounds is also characterized by synergistic effects which are difficult to estimate. They are an underestimated danger to the environment and to the human population. This paper presents an in-vivo model enabling to assessment of the real impact of exposure to hormonal compounds and the synergistic effect which can be involved. The anatomical effects of in-ovo exposure to two natural estrogen compounds (estrone and estriol, at 600 ng g−1) and a synthetic estrogen (ethynylestradiol, at 20 ng g−1) have been investigated. Estrone and estriol lead to morphological defects, mainly in the urogenital system of the developing chick embryo, whereas ethynylestradiol has fewer effects. Estriol caused persistence of Müllerian ducts in 50% of male embryos and hypertrophic oviducts in 71% of females. Estrone had the same effects but at the percentages were lower. Kidney dysfunction was also observed, but only with estrone, in both males and females. We also tested estrogenic compounds in two types of cell line which are estrogen sensitive (BG1 and MCF7) then completed and confirmed our previous in-vivo results. Seven pharmaceutical-like compounds—estrone (E1), estradiol (E2), estriol (E3), ethynylestradiol (EE2), carbamazepine (C), genistein (G), and bisphenol-A (BPA)—were tested alone or in mixtures. Different effects on the two cell lines were observed, indicating that endocrine compounds can act differently on this organism. Experiments also showed that these molecules have synergistic action and induce more severe effects when they are in mixtures