The   “Hellenic Thesaurus of  Scientific Terms”   is a modern terminological tool that is used to describe the subject content of resources and provide access to the documents and the information resources of   HEAL-Link. It can be used in the organization of  the Online Public Access Catalogs (OPACs)   of  HEAL -Link, of  the  Hellenic Academic Libraries Union Catalog, to the subject  description and searching  for  information in their digital repositories as well as in future projects  to produce and manage digital content.