The results of a study of the microdistribution of silicon and copper in the matrix of a magnesium cast iron in the cast state after isothermal treatment and normalization are considered. It is established that copper, although it ensures structural homogeneity of the cast iron matrix, does not lead to chemical homogeneity of the matrix. Normalization and isothermal treatment have little effect on the microdistribution of silicon and copper, although they improve the mechanical properties of the cast iron.