ISG

ISG may refer to:

The Iraq Survey Group for the investigative group in Iraqi's WMD program
The International Socialist Group which is a small Trotskyist group.
Interferon-Stimulated Genes, genes whose transcription is stimulated by interferons
International Steel Group, a steel company headquartered in Cleveland, Ohio.
An Interactive Storytelling Game, a type of role-playing game.
The International Support Group, a non-profit professional association registered in the Netherlands.