Shear rate is significantly lower in the superficial femoral compared to the brachial artery in the supine posture. The relative shear rates in these arteries of subjects in the upright posture (seated and/or standing) are unknown. The purpose of this investigation was to test the hypothesis that upright posture (seated and/or standing) would produce greater shear rates in the superficial femoral artery compared to the brachial artery. To test this hypothesis, high resolution Doppler ultrasound was used to measure mean blood velocity (MBV) and diameter in the brachial and superficial femoral arteries of 21 healthy subjects after being in the supine, seated and standing postures for 10 minutes. There were no significant differences in MBV between the two arteries or across the three postures. Superficial femoral artery diameter was significantly larger than brachial artery diameter. However, posture had no significant effect on either brachial or superficial femoral artery diameter. Calculated shear rate was significantly greater in the brachial (73 ± 5; 91 ± 11; 97 ± 13 s-1) compared to superficial femoral artery (53 ± 4; 39 ± 77; 44 ± 5 s-1) in the supine, seated and standing postures, respectively. Contrary to our hypothesis, our current findings indicate that shear rate is lower in the superficial femoral artery when compared to the brachial artery in the supine, seated and standing postures. These findings of lower shear rates in the superficial femoral artery maybe one mechanism for the higher propensity for atherosclerosis in the arteries of the leg than arm.