The hydroxy-methylglutaryl coenzyme A reductase (HMGR) is the rate-limiting enzyme in cholesterol synthesis and can be phosphorylated and inactivated by the AMP-activated protein kinase (AMPK). Given that fluid shear stress activates the AMPK, the focus of the present study was to determine whether shear stress can modulate the activity and/or expression of HMGR in endothelial cells. The application of fluid shear stress (12 dynes/cm2, 2 h), as well as the overexpression of a constitutively active AMPK (CA-AMPK), decreased HMGR activity in cultured endothelial cells. Inhibition became more pronounced with time (up to 24 h), indicating an additional effect on the expression of the HMGR. In endothelial cells, shear stress decreased HMGR mRNA levels to about 30% of control. Fluid shear stress as well as CA-AMPK also concomitantly increased the phosphorylation and decreased the expression of the transcription factor FOXO-1A. The down regulation of FOXO-1A using a siRNA approach also decreased HMGR mRNA expression to a similar extent (30%) as shear stress. These data demonstrate that shear stress, by activating AMPK, not only inhibits HMGR activity, but also initiates the decrease of HMGR mRNA levels by a pathway involving the phosphorylation and degradation of FOXO-1A in endothelial cells.