The contribution deals with the phrasicon of Esperanto, i.e. the inventory of idioms, phrases, proverbs, catchphrases and other items of pre-fabricated speech that are stored in speakers' mental lexicon. On the basis of origins, Esperanto phraseology can be classified into three groups: First, many phraseological units have entered the language through various other languages. This group includes classical loan translations especially from the Bible as well as ad-hoc loans introduced by speakers from their mother tongues more or less spontaneously. Secondly, there is a group of planned, i.e. consciously created, phraseological units. They mainly go back to Zamenhof, the initiator of the language, who published an Esperanto Proverb Collection (Proverbaro Esperanta) in 1910. Thirdly, there are phraseological units which have their origin in the language and the cultural life of the speech community. The paper will show that the planned language Esperanto, with its agglutinative character, free word order and flexible word formation, possesses the prerequisites for creating stylistically appealing and catchy phraseological units. An analysis of literary and journalistic texts as well as oral communication in Esperanto reveals that its phraseology is widely used and that authors like to modify phrases and idioms according to the textual situation. The use of phraseological units proves that Esperanto is a living language. Phraseology can be considered a criterion for assessing the successful development of the planned language system from a project to a full-fledged language. It demonstrates the complexity of Esperanto culture.