This review article is dedicated to a relatively young, actively developing approach to biodiversity assessment – analysis of environmental DNA (or eDNA). Current views on the nature of eDNA, a brief overview of the history of this approach and methods of eDNA analysis are presented. Major research directions, utilizing eDNA techniques, and perspectives of their application to the study of biodiversity are described. Key issues in development of eDNA approach, its advantages and drawbacks are outlined.