Fe_0.5MnNi_1.5CrNb_x (x=0, 0.05, 0.1, molar ratio) high-entropy alloys were prepared by vacuum induction melting. The effect of Nb content on the microstructure and mechanical properties of the new alloy was analyzed. The results show that the Nb-free alloy has a single-phase fcc structure, and its tensile strength and elongation to failure (i.e., ductility) are 519 MPa and 47%, respectively. With the addition of Nb (x=0.05), the (200) texture and Fe₂Nb Laves phase appear. The ductility of alloy increases to 55%, while the tensile strength increases to 570 MPa. When the molar ratio of Nb increases to 0.1, the texture diminishes, whereas the volume fraction of the Fe₂Nb phase is increased. The resultant tensile strength and ductility are 650 MPa and 45%, respectively.