Study and conservation of biodiversity is impossible without correct identification of organisms. Construction of keys is thus a very important task. If this is done with computers the resulting keys can be accessible for users with different levels of knoweledge. In 1997 we began to construct a computerized polythomyc multi-entrance key for the identification of Artemisia L. species in Ukraine. The database driving the identification system is built on relational links between four tables. These tables deal with species, characters rows, the characters themselves, and links. There are two modes for working with the main database. One is data-entry and the editing of characters; the other is identification of species by those characters. It was not possible to construct this polithomic key solely from information in floras and similar publications because they contain many relative characters, and incomplete or even erroneous descriptions. Difficulties can also arise from inconsistencies in usage of terms in botanic literature. During key construction, therefore, terms were standardized and illustrated were possible. Simple and complex morphological features are used in the key, and additional characters are provided in the key to permit identification through various selections (Savchenko, 1997). When the user formulates an inquiry the relevant species is automatically selected. Monotypic standards were adopted and the database contains information on the ecology and geography of every species. The software uses the FOXPRO 2.2 database system for MS DOS, and the program contains a hierarchical arrangement of menus, and has an autohelp line for each stage of the work. The main principles of key construction in this work are therefore that it is polythomic, multi-entrance, and interactive; it uses ecologcal and geographical information as well as morphological characters; it provides illustrations of problematic characters; and it uses both simple and more complex characters.