Preclinical data have demonstrated that heart rate (HR) can directly impact vascular endothelial function, in part, through a shear stress mechanism. This study sought to explore, in humans, the associations between resting heart rate and both shear and endothelial function assessed by flow-mediated dilation (FMD). The brachial artery FMD test was performed in 31 apparently healthy volunteers. Basal (B) and hyperemic (H) shear were quantified two ways using data from the FMD test: the traditional cumulative shear area under the curve up until peak dilation (Shearcum) method, and our novel method of shear summation (Shearsum), which accounts for HR by summing each individual cardiac cycle shear up until peak dilation. Data were grouped by tertiles based on resting HR: low (LHR = 43 – 56 bpm; n = 10), middle (MHR = 58 – 68 bpm; n = 11), and high (HHR = 69–77; n = 10), respectively. Within the LHR group, both B-Shearcum and H-Shearcum were significantly higher (p<0.001) than B-Shearsum and H-Shearsum, respectively, whereas B-Shearcum and H-Shearcum were significantly lower (p<0.001) than B-Shearsum and H-Shearsum in the HHR group. FMD in the LHR group (8.8±0.8%) was significantly greater than both the MHR (5.5±0.8%; p = 0.009) and the HHR group (5.9±0.8%; p = 0.024). These findings demonstrate the existence of a relationship between heart rate and both shear and endothelial function in humans. Moreover, these findings have implications for considering heart rate as an important physiological variable when quantifying shear and performing the FMD test.This article is protected by copyright. All rights reserved