The study described here focuses on the microstructure and mechanical properties of a novel hot-rolled medium-Mn steel (Fe-0.25C-4Mn-1.88Al-0.6Si-0.04Nb-0.08V, wt%) that contained only 4 wt% Mn and modest Al content of 1.88 wt%. It was found that a relatively high content (25-53 vol%) of retained austenite was obtained by intercritical annealing process. With increase in intercritical annealing temperature from 700 to 740 and to 760 A degrees C, retained austenite fraction increased from 25.1 to 53.2% and then decreased to 46.1%. Besides, mechanical stability of retained austenite in 700-760 A degrees C intercritically annealed steels decreased with increase in intercritical annealing temperature. The 720 A degrees C intercritically annealed steel yielded excellent mechanical properties with yield strength of 766 MPa, tensile strength of 951 MPa, total elongation of 48.6% and PSE of 46.22 GPa center dot%, achieved by a high volume fraction of retained austenite (46%) with relatively high mechanical stability. Thus, the 4% Mn steel present in this study indicated excellent mechanical properties of medium-Mn steels can be achieved using low alloy content.