The research objective was studying by method of electrophoresis of prolamin the change of biotype struc-ture of summer triticale varieties in the course of cultiva-tion in the conditions of Tyumen Region. As the material for research individual kernels of spring triticale varieties Ulyana and Solovei Kharkovsky, cultivated on experi- mental field of Northern Trans-Urals SAU served. As a result of electrophoretic separation of prolamines, it was established that both varieties were heterogeneous in gliadin component composition. In the spectra of the variety Ulyana, 14 types of spectrum were found, and the varieties Solovei Kharkovsky - 5. When comparing obtained electrophoretograms with the standard spectra of varieties, it was established that 4 of detected types of the spectrum of the variety Solovey Kharkovsky and 12 of the variety Ulyana were not typical for them. The amount of impurity was from 27 % in the variety Ulyana to 36 % in the variety Solovei Kharkovsky. As a result of the construction of dendrogram based on the data on the component composition of gliadin it was established that the biotypes of varieties Ulyana and Solovei Kharkovsky were combined into two different subclusters. Genetic distance between all detected bio- types ranged from 0 to 0.3 in Ulyana variety and up to 0.1 in Solovei Kharkovsky variety. A relatively small amount of genetic distance between biotypes of one variety indicated predominantly biological clogging of varieties. The appearance of new biotypes in investigat- ed varieties was caused by a variety of reasons, from residual heterozygosity to spontaneous intraspecific hybridization and mechanical contamination. To main- tain genetic stability of triticale varieties and timely de- tection of mechanical and biological contamination in the process of cultivation regular monitoring of the bio- type composition of varieties by the method of prolamin electrophoresis is necessary.