Cardiovascular control during exercise is regulated in part by reflex feedback from muscle afferent nerve fibres (McCloskey and Mitchell, 1972). Isometric handgrip exercise causes renal vasoconstriction in humans (Middlekauff et al., 1997) and this effect is augmented in older, healthy humans (Momen et al., 2004). However, it is unknown whether healthy ageing augments renal vasoconstriction during isometric calf exercise. Exaggerated renal vasoconstriction occurs during mild, plantarflexion exercise in peripheral arterial disease patients (Drew et al., 2013) so elucidating the effect of ageing alone on renal responses during leg exercise is of clinical relevance. Therefore, this study examined renal vascular responses during isometric, calf exercise in healthy young and older humans. Twelve young, healthy (Young; 6 men; mean ± SEM 25 ± 1 y) and ten older, healthy (Older; 4 men; 62 ± 1 y) subjects rested for 5 minutes, then performed 1.5 minutes of one-legged, isometric, calf exercise at 70% maximal voluntary contraction (MVC). Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer) and heart rate (HR; ECG) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Statistical analysis involved independent t-tests and two-way ANOVA. Baseline RBFV and HR were similar between Older and Young (Older: 54.9 ± 3.8 vs. Young: 56.7 ± 2.3 cm.sec-1 and Older: 60 ± 2 vs. Young: 63 ± 2 b.min-1). Baseline MAP was significantly higher in Older compared to Young (Older: 100 ± 3 vs. Young: 87 ± 2 mmHg; P<0.05), therefore RVR tended to be higher in Older compared to Young (Older: 1.9 ± 0.1 vs. Young: 1.6 ± 0.1 arbitrary units; P=0.06). By the end of 70% MVC exercise, Older demonstrated a similar increase in MAP (Older: 10 ± 2 vs. Young: 9 ± 2 mmHg) but an attenuated increase in HR (Older: 6 ± 1 vs. Young: 14 ± 3 b.min-1; P<0.05) compared to Young. Of note, Older exhibited a greater decrease in RBFV (Older: -11.2 ± 1.6 vs. Young: -3.8 ± 1.4 cm.sec-1; P<0.05) compared to Young by the end of 70% MVC exercise, which precipitated an augmented increase in RVR (Older: 39 ± 5 vs. Young: 20 ± 3 %; P<0.05) in Older compared to Young by the end of exercise. In conclusion, these findings suggest that renal vasoconstriction during isometric, calf exercise is augmented in older, healthy humans. This exaggerated renal vasoconstriction during exercise in older people appears driven by a greater reduction in renal blood flow rather than an accentuated increase in systemic blood pressure.