This work investigates the effect of chemical composition on the microstructure and properties of cast high-entropy alloys, and optimal conditions for homogenization annealing. The investigation is performed on alloys of the following compositions: Fe22.5Ni22.5Cu22.5Co22.5Al10, Fe22.5Ni22.5Cu22.5Cr22.5Al10, and Fe22.5Ni22.5Cu22.5Mn22.5Al10 (shortly Fe22.5Ni22.5Cu22.5(Co, Cr or Mn)(22.5)Al-10), melted in an induction furnace with casting into a copper mold. The structural and phase changes in high-entropy alloys of different chemical composition are examined before and after homogenization annealing. The morphology of crystalline phases and microstructural evolution are analyzed experimentally. The strength characteristics of the alloys subjected to different homogenization annealing conditions are determined.