This article deals with the use of illustration as intersemiotic translation in dictionaries of French slang. Even though the presence of illustration may suggest a lack of intralingual translation on which slang dictionaries are built, it shows as we shall see, that illustration becomes an intracultural mediation’ mechanism for the French reader. The different types of illustration used by dictionaries’ writers are also examined. In the dictionaries of French slang that were analysed, it seems that illustration aims at providing a semantic orientation for the treatment of slang lexemes and their consolidation in the collective cultural memory. Similarly, the diverse forms of illustration show how valorise they are in intralingual communication.