The results of the study of the interaction of genetic and radiation factors in the effects of radiation in humans exposed to external and (or) internal radiation are presented. In most cases, with relatively less radiation exposure genotypic differences in the effects of exposure were established to be absent. At high intensities of radiation exposure, however, these differences as a rule have reliable character. Interaction of genetic and radiation factors manifested in a wide range: from the mutual stimulation of primarily inactive factors to the higher than multiplicative one.