Using electrophoresis, in 114 recombinant hybrid lines of the mapping population of spring bread wheat and in 2 parental forms, 7 esterase isoenzymes were found: A1-A7 (Mr 93-138 kDa). According to their esterase composition, all samples were subdivided into 17 zymotypes. Isoforms A4 and A6 are pre-sent in all zymotypes, i.e. are monomorphic. The other 5 isozymes provide a high level of polymorphism in the population. The majority of genotypes belong to the zymotype Gr. 1 (27%), which includes 6 isoforms. Among them there are isoforms A1 and A7, characteristic only for each of the parent forms, which indicates the codominant inheritance of these isoenzymes.