The article presents the results of a study into the activity of the antioxidant system of potatoes in response to infection with the PVS virus. The PVS virus is widespread in the Omsk region. The work set out to study the activity of antioxidant enzymes in somaclonal potato variants when infected with PVS virus to obtain valuable varietal characteristics for use in breeding selection. Potato varieties Yermak, Alena and the Khozyayushka were selected from the Omsk Agrarian Scientific Centre breeding lines as objects of research. Differences in resistance to viral infection in varieties of different susceptibility and obtained somaclones were studied using the example of changes in the activity of the isoenzyme composition of antioxidant enzymes. The results showed that somaclone EC1, which was derived from the susceptible Yermak variety, had two additional isoenzymes upon infection and an increase in isoperoxidase activity compared to the control. Although the number of isoperoxidases did not increase in the samples obtained from the stable HC94 and the moderately susceptible AC91 variety, an increase in their activity was noted. Activation occurs in infected plants of the additional 3rd isoforms of catalase compared to the control – 1 isoform, while the 4th isoform of catalase was detected in the EC1 somaclonal sample. When studying the superoxide dismutase spectra, the control group showed the activity of Mp-SOD and Fe-SOD, while two forms of the enzyme were identified in the HC94, AC91 and EC1 somaclonal samples: Feand Cu/Zn-SOD. These forms play a significant role in the neutralisation of the superoxide radical.