Objectives. Whole blood viscosity (WBV) may promote endothelial shear stress, endothelial inflammation, and vascular remodeling, and can accelerate the atherosclerotic process. We aimed to evaluate the relationship between WBV and Aortic Stenosis (AS). Methods. The study population included 209 participants of which 49 patients with severe AS, 98 patients with mild-to-moderate AS and 62 patients as control. The WBV calculated with a formula from Hct and total plasma protein (TP) for wall shear stress. WBV was cal-culated for both low shear rate (LSR) (0.5 s–1) and high shear rate (HSR) (208 s–1) from Hct and TP protein concentration using a validated formula. Results. WBV values were significantly higher for HSR (p = 0.001) and for LSR (p=0.002) in severe aortic stenosis group than mild-to-moderate aortic stenosis group. HSR and LSR were correlated with mean systolic transaortic gradient (p<0.001 and p<0.001, respectively). WBV for both LSR and HSR were found to be independent predictors for the aortic stenosis severity (β=0.265;p=0.034 and β=0.237;p=0.049, respectively). Hypertension independently associated with the aortic stenosis severity (p<0.05). Conclusion. We found a significant relationship between WBV and AS