The effects of shear stress on interleukin 8 (IL‐8) production by human umbilical vein endothelial cells (HUVEC) were studied by subjecting the HUVEC to a steady flow laminar shear stress of up to 0.7 N/m 2 in a parallel plate flow chamber. Shear stress decreased IL‐8 mRNA expression in a dose and time‐dependent fashion. High glucose concentrations increased IL‐8 mRNA levels in a MAPK‐p38‐dependent manner, which was suppressed by shear stress. Measurement of IL‐8 protein in HUVEC culture media by ELISA demonstrated that IL‐8 secretion was also increased by high glucose and suppressed by shear stress. These results suggest that the anti‐atherogenic effect of shear stress arises partly from the suppression of the production of IL‐8 which has been shown to trigger the adhesion of monocytes to a vascular endothelium and also acts as a mitogen and chemoattractant for vascular smooth muscle cells.