Abstract The paper deals with the exponent of hyperbolic decrease in a regenerative system's reliability as the function of the similar exponent of its nonvitality. Ecological bases for the hyperbolic law of the decreasing nonvitality of the system are provided. Stochastic models of the system's death at metabolic and structural levels, as well as a general model of its death are considered. The minimum order of the increase in the number of the system's elements as function of its age is found to result in its reliability arbitrary close to unity. This order is of logarithmic and logarithmic-power nature. Biological effects of the regularities so discovered are discussed.