Low birth weight infants, in particular those born preterm, have been shown to develop increased arterial blood pressure and hypertension at adulthood. Three main systems are involved in the developmental programming of hypertension: the kidney, the neuroendocrine system, and the vascular tree. This review focuses on vascular dysfunction and discusses clinical and experimental evidence that relates low birth weight and the risk for hypertension at adulthood. Recent studies demonstrate an impairment of vascular structure and function. Both arterial vessels, through altered arterial stiffness and endothelium-dependent vasodilation, and the capillary bed, through microvascular rarefaction, are involved in the early pathogenesis of hypertension. The key role of the endothelium, as shown by altered vasodilatation, angiogenesis, endothelial progenitor cells, and microparticle number and function, is discussed as a possible explanatory mechanism.