Within the bounds of the complex research of herbaceous plants in the EURT zone of the allozyme variability, total content of low-molecular antioxidant (LMAO) are studied and vitality, mutability and radiosensitivity of seed progeny of Melandrium album (Mill.) Garcke is estimated. Based on allele’s frequency the values of the main indicators of genetic variability of species were obtained. The significant shift of allele’s frequency in chronically irradiated populations among 13 polymorphous loci was discovered in only two systems - NADHdh and LAP. For the cenopopulations of the EURT zone the tendency of decrease of seed progeny survival rate was observed in radionuclide contamination gradient. Seed progeny mutability of chronically irradiated cenopopulations in the majority of deviance in development was signficantly higher than that in background sample that indicates the increase of genetic load. It is detected that the stronger is the radiation stress on the cenopopulations, the more low-molecular antioxidant the acrospires contain. The hightened content of LMAO in the seedlings from the radioactive-contaminated territories allows to suggest that the systems of antioxidant protection of the acrospires of herbaceous plants work more tensely to struggle against free radicals constantly generated during the dissociation of incorporated radionuclides. The effect of radioadaptation of the species studied is not detected.