The ability of the human body to maintain arterial blood pressure (BP) during orthostatic stress is determined by several reflex neural mechanisms. Renal vasoconstriction progressively increases during graded elevations in lower body negative pressure (LBNP). This sympathetically mediated response redistributes blood flow to the systemic circulation to maintain BP. However, how healthy aging affects the renal vasoconstrictor response to LBNP is unknown. Therefore, ten young (25 ± 1 years; mean ± SE) and ten older (66 ± 2 years) subjects underwent graded LBNP (-15 and -30 mmHg) while beat-to-beat renal blood flow velocity (RBFV; Doppler ultrasound), arterial blood pressures (BP; Finometer), and heart rate (HR; electrocardiogram) were recorded. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as mean BP/RBFV. All baseline cardiovascular variables were similar between groups, except diastolic BP was higher in older subjects (P < 0.05). Increases in RVR during LBNP were greater in the older group compared to the young group (older: -15 mmHg 10 ± 3%, -30 mmHg 20 ± 5%; young: -15 mmHg 2 ± 2%, -30 mmHg 6 ± 2%; P < 0.05). RBFV tended to decrease more (P = 0.10) and mean BP tended to decrease less (P = 0.09) during LBNP in the older group compared to the young group. Systolic and diastolic BP, pulse pressure, and HR responses to LBNP were similar between groups. These findings suggest that aging augments the renal vasoconstrictor response to orthostatic stress in humans.