KEY POINTS: Maternal hypoxia is a common perturbation that leads to growth restriction and may program vascular dysfunction in adult offspring. An adverse prenatal environment may render offspring vulnerable to increased cardiovascular risk when challenged with a second hit , such as a high salt diet. We investigated whether maternal hypoxia impaired vascular function, structure and mechanics in mouse offspring, and also whether this was exacerbated by excess dietary salt intake in postnatal life. Maternal hypoxia predisposed adult male and female offspring to endothelial dysfunction. The combination of prenatal hypoxia and high dietary salt intake caused significant stiffening of mesenteric arteries, and also altered structural characteristics of the aorta consistent with vascular stiffening. The results of the present study suggest that prenatal hypoxia combined with a high salt diet in postnatal life can contribute to vascular dysfunction. ABSTRACT: Gestational hypoxia and high dietary salt intake have both been associated with impaired vascular function in adulthood. Using a mouse model of prenatal hypoxia, we examined whether a chronic high salt diet had an additive effect in promoting vascular dysfunction in offspring. Pregnant CD1 dams were placed in a hypoxic chamber (12% O2 ) or housed under normal conditions (21% O2 ) from embryonic day 14.5 until birth. Gestational hypoxia resulted in a reduced body weight for both male and female offspring at birth. This restriction in body weight persisted until weaning, after which the animals underwent catch-up growth. At 10 weeks of age, a subset of offspring was placed on a high salt diet (5% NaCl). Pressurized myography of mesenteric resistance arteries at 12 months of age showed that both male and female offspring exposed to maternal hypoxia had significantly impaired endothelial function, as demonstrated by impaired vasodilatation to ACh but not sodium nitroprusside. Endothelial dysfunction caused by prenatal hypoxia was not exacerbated by postnatal consumption of a high salt diet. Prenatal hypoxia increased microvascular stiffness in male offspring. The combination of prenatal hypoxia and a postnatal high salt diet caused a leftward shift in the stress-strain relationship in both sexes. Histopathological analysis of aortic sections revealed a loss of elastin integrity and increased collagen, consistent with increased vascular stiffness. These results demonstrate that prenatal hypoxia programs endothelial dysfunction in both sexes. A chronic high salt diet in postnatal life had an additive deleterious effect on vascular mechanics and structural characteristics in both sexes.