The paper describes the structure of the electronic database «Habitats of East Fennoscandia», its structural principles and potential applications. The database was originally created as a tool to support digital biological collections, meant to formalize the ecological conditions of the sample collection or description. In the scheme proposed, habitats are distinguished by two major features: ecotope and vegetation. In addition, the human impact is taken into account. All in all, six classes of habitats (top unit in the classification hierarchy) were distinguished for Karelia: Sea and sea coast, Lakes and shore habitats, Rivers, streams and related habitats, Wetland habitats, Well-drained habitats in water divide areas and Anthropogenic habitats. As the database grew more advanced, it began to be used for classification of plant communities, GIS development, identification of rare habitats and habitats of rare plant and animal species. The system used for input of plant species after which the habitat type is named and determined, as well as dual codes for biotope types help avoid errors in the search for and identification of biotope types, and make the database usable for a wide range of specialists.