The present study compared the hemorheological properties between Epo-TAgh mice (a model of erythropoietin deficient mice) and wild-type (WT) control mice. Blood viscosity was determined at several shear rates using a cone-plate viscometer at native and adjusted hematocrit (i.e. 40%). Red blood cell (RBC) deformability was measured by ecktacytometry at several shear stresses and RBC aggregation properties by backscattered technique at adjusted hematocrit (i.e. 40%). Epo-TAgh mice had severe anemia (very low hematocrit), decreased blood viscosity at native hematocrit and slightly reduced RBC deformability at high shear stresses in comparison with WT mice. Blood viscosity at adjusted hematocrit (i.e. 40%) was not different between WT and Epo-TAgh mice. RBC aggregation did not differ between the two mice models. These findings suggest a role of erythropoietin in the regulation of RBC deformability.