Mg deficiency is considered as a risk factor of cardiovascular disorders like hypertension and atherosclerosis. NIGH and MGL juice, selected for high and low Mg status, are animal models which present variations of Mg metabolism of genetic origin. The cardiovascular functions of these mice have never been studied. In this study, the arterial blood pressure of NIGH and MGL strains was measured by plethysmography. Morphology and reactivity to vasoconstrictor agents were also investigated by a pressurized and perfused system in mesenteric resistance artery. 11: is shown that: (1) MGH mice presented a higher plasma Mg concentration than MGL; (2) arterial blood pressure and heart rates were similar between the two groups;, (3) media thickness, media cross-sectional area, and internal and external diameters were smaller in pressurized mesenteric resistance arteries from MGH mice than in those front MGL mice; (4) the vasoconstriction induced by vasopressin (but not norepinephrine) was higher in the mesenteric arteries from MGH mice than in those front MGL ones. In summary, MGH mice as compared to MGL mice present differences in arterial geometry and higher reactivity to vasopressin without repercussions on arterial blood pressure. The real repercussion of these observations oil the cardiovascular system of the NIGH and MGL models is at present unknown. More experiments are needed to clarify the influence of differences in Mg metabolism of genetic origin oil cardiovascular function.