Аннотация:At present, practical application of the method of biological indication for environmental assessment purposes is limited by the poor development of formal procedures for interpreting the results of biological indication in terms of ecosystem quality. Existing approaches to the interpretation of biological indication data on terrestrial, aquatic, and soil ecosystems have been classified with respect to the increasing degree of their formalization into groups of (1) expert estimates, (2) statistical treatment of large data sets, (3) multiple biological indication at different levels of ecosystem organization, (4) analysis of the dose-response relationships, and (5) ecological modeling. For practical reasons, the method of multiple biological indication is considered optimal for unambiguous identification of the state of impacted ecosystems. This method involves appropriate data formalization and consistent rules for their ecological interpretation.