Polyacrylamide-slab gel electrophoresis of peroxidases of different Triticum and Aegilops species and of nullisomic–tetrasomic lines of Chinese spring wheat showed that T. aestivum chromosomes 7D, 4B, and 7A are the carriers of genes coding the synthesis of peroxidase a, peroxidase c, and peroxidase d, respectively. The indirect effect of modified chromosome systems and a special effect of chromosome 5B on peroxidase synthesis have also been observed. The chromosomal and genomic origin of the three other peroxidases (b, e, and f) detected in common wheat could not be definitively established.