Criteria for quantitatively describing the state and state variation of a living organism in various conditions are proposed using a set of its measurable characteristics (indicators, properties). The measurable indicators (of diff erent origin and dimensionality) of an organism converted into a dimensionless form relative to their control values are combined into a single integral indicator showing relative deviation averaged over all the indicators. This integral indicator is useful to compare the results of diff erent experiments. If the range of normal variability (reference range) is known for each indicator involved, the second integral indicator is proposed to be calculated as the normalized relative deviation from the middle of all reference ranges (in percentage) averaged over all the indicators. The calculation is performed in such a way that the range 0–100 % of this deviation of an indicator corresponds to the normal variability (where 0 corresponds to the middle of the reference range, 100 % – to its lower or upper limit), while the values over > 100 % represent a pathological response. The normalized relative deviation from the middle of all reference ranges (in percentage) averaged over all the indicators is an assessment of the state of a living organism (based on the given set of indicators) relative to the range of normal variability. The application of the suggested approach is illustrated by an example of a toxicological experiment.