[en] An analysis of stochastic radiobiological effects of low-dose exposure of different biological objects has been carried out. The analysis has been carried out on the basis of the two-protection reaction model. The model leans upon the accepted scheme of the principal stochastic radiobiological process and uncontradictorily describes accessible data. The analysis shows that the yield of initial damages, in such structures as DNA, follows the linear no-threshold (LNT) relationship dose-effect. The resulting effect also follows the LNT relationship, provided that there is no reparation process or its suppress. The action of inducible or adaptive protective mechanisms, having restricted possibilities, leads to non-linear relationship dose-effect. The power of non-linearity is determined by the nature of the biological object, degree of damage, exposure conditions and level of the spontaneous effect. (author)