WordNet is an on-line lexical database of English language. Word meanings are represented by synonym sets (synsets). Each synset corresponds to one lexical concept. Different lexical and semantic relations link the synsets. An algorithm for automated forming Bulgarian synsets, corresponding to WordNet synsets, is presented. The three main steps of the algorithm are: I Automated improving of synsets on synonym dictionary that includes discovering synsets representing one concept; synsets which contain words for two or more different concepts; synsets with missed or incorrect synonyms placed in them, etc.; II. Finding a correspondence between lines of Englilish-Bulgarian Dictionary and WordNet synsets; III. Forming Bulgarian synsets coresponding to 55,000 WordNet concepts, using results from steps I. and II.