The cyclin-dependent kinase inhibitor p57^kip2 regulates the cell cycle of trophoblastic cells. It has been established by a Japanese group that the heterozygous p57^kip2 knock-out (p57^-/+) mice are a good model of preeclampsia as they develop hypertension, proteinuria and placental pathology. However, apart from the placental pathology, we could not observe these symptoms in our laboratory. Hence, we investigated the impact of diet and stress on this model. To do so, we compared the effects of the Japanese diet to that of the North American diet used by our animal facility. Furthermore, the impact of stress was determined by placing the mice in a restraining device before and at the end of gestation. Although the Japanese diet did not have any impact on blood pressure or proteinuria, the mice did develop endothelial dysfunction, left ventricular hypertrophy, as well as had increased placental pathology. Also, all mice had smaller litters when fed the Japanese diet. However, stress response of these mice was not increased during gestation, in fact, a decrease was observed in the p57^-/+ mice suggesting that this was probably not a player in the development of the pathology. Taken together, these results suggest that other environmental factors may have been implicated in the development of preeclampsia-like symptoms in this animal model. Moreover, we demonstrated that placental pathology and genetic factors are not sufficient to trigger preeclampsia-like symptoms in this model, and that the diet might play an important part in the development of this multifactorial disease.