The genetic stocks of SURES-1 and SURES-2 showed complete tolerance to tribenuron-methyl. No resistance were obtained after observation on 200000 plants of four VNIIMK breeding lines grown on an experimental field with total area of 5 ha treated with Express at 1x rate. Potential frequency of a dominant gene for tolerance to tribenuron-methyl was estimated less than 5×10 −6 . Moreover screening both of 700 plants of 39 inbred lines of the genetic collection and 800 plants of M 2 four breeding lines did not reveal any resistance. Tolerance to tribenuron-methyl in F 1 and F 2 in the crosses of SURES-1 and SURES-2 with VNIIMK breeding lines was controlled by one dominant gene. All recessive homozygous hybrid plants of sur sur genotype in the cross were dead with phytotoxicity index of 9 after Express treatment at any rate of tribenuron-methyl from 0.5x to 4x. Heterozygous hybrid plants of Sur sur genotype showed no injury symptoms at 0.5x rate and increasing level of phytotoxicity index of 4 6 and 7 for 1x 2x and 4x rates correspondingly. Dominant homozygous hybrid plants of Sur Sur genotype possessed no injury symptoms from 0.5x to 2x rates whereas the phytotoxicity index of 4 was observed at the 4x rate. Consequently there was no difference between dominant homozygote Sur Sur and heterozygote Sur sur with phytotoxicity index of 0 at 0.5x rate. Allelic interaction in a heterozygote Sur sur can vary from complete to partial dominance in accordance with increasing rate of tribenuron-methyl treatment estimating with the phenotypic scale of phytotoxicity index.