Thesaurus, a well-known form of controlled vocabulary, has been widely used for indexing and searching of information during the last 50 years. There also have been developments of international and national standards to provide guidelines for developing thesaurus in diverse subject areas. In recent years, the revisions of thesaurus-related standards have been made. Among them are ISO 25964 and BS 8723. This article examines the current status of revision of these standards, and discusses its implications. Based on this examination, it suggests functional requirements of thesaurus in the present information environment, and also proposes elements needed for the development of these functions.