Aim. We do analyze of the dynamics of morphometabolic changes in transformed cells (of susceptoible lines) demonstrating resistance to picrnaviral infection. Methods. The study was performed by application of cell culture technology and a complex of cytochemical and cytophotometric assays. Were used picornaviruses from various genu. Results. According to the results obtained, resistant to picornavirus infection cells of different susceptible lines have similar changes in the phenotype. They have decreased number of nucleoli and increased percentage of euploidy (and near euploid). In resistant cells of all cultures the reduction in amount of DNA and RNA both in nucleus and in cytoplasm was found. All these data correlated with the increased euploidy (and near euploid) of the resistant population. All picornavirus resistant cells had a less transformed phenotype, and decreased proliferative activity. Decreased nucleolar status becomes apparent by reduction of all nucleolar indices. Conclusions. Picornaviruses on the susceptible cells produce 2 types of changes – selection and modification. Whatever the mechanism, it is specific for an individual virus, since no restrictions occur in case of infection caused by another picornavirus

Keywords: picornavirus, euploidy, nucleus, nucleolus