Two high carbon steels, 1.27% C and 1.24%C-12%OMn, have been rolled isothermally at 930K. The tensile and the fatigue strengths were investigated. The tensile strength and the ductility for 1.27% C steel were improved by the warm rolling. On the other hand, for 1.24%C-12%Mn steel the tensile strength was raised at the expense of ductility. The fatigue strength of warm rolled steel was superior to that of forged steel. The fatigue ratio was improved by warm rolling, although the notch sensitivity was almost similar for both steels.