A novel method to develop new quaternary alloys with an fcc/L12 coherent structure is proposed. This paper reviews the development of quaternary Ir-Nb-Ni-Al alloys. The microstructure, lattice misfit, and compressive 0.2% flow stress of 15 kinds of alloys were investigated systematically. Two kinds of coherent structures, fcc/L12-Ir3Nb and fcc/ L12-Ni3Al, were observed in most alloys. Two two-phase structures, fcc+L12-Ir3Nb and fcc+L12-Ni3Al, were observed in Ir-rich and Ni-rich regions, respectively. The lattice misfits of quaternary Ir-Nb-Ni-Al alloys were higher than those of Ni- or Ir-base binary alloys. The compressive 0.2% flow stresses of quaternary alloys increased dramatically compared with those of Ni-base superalloys. The quaternary alloys located in the Ir-rich region were not only had higher strength but also better ductility than Ir-base binary alloys. The potential use of quaternary alloys is discussed.