Pre-eclampsia is a maternal pathology, specific to pregnancy, secondary to placental dysfunction occurring from the second trimester onwards, and specific to human gestation. The causes of this placental dysfunction are highly variable, making the experimental approach to this pathology highly complex. Placental dysfunction is responsible for the release into the maternal circulation of substances responsible for endothelial dysfunction, characterized by activation of endothelial cells and increased vascular permeability. It appears to be a two-stage disease, with an initial stage of placental syndrome followed by maternal syndrome. The maternal syndrome in preeclampsia corresponds to a state of generalized endothelial dysfunction secondary to an excess of circulating factors toxic to the endothelium which are released by the pathological placenta. Understanding the mechanisms leading to placental ischemia in pre-eclampsia should shed light on the pathogenesis of pre-eclampsia.