IAH may refer to:
- George Bush Intercontinental Airport (IATA code), an airport in Houston, Texas
- Iah, a god of the moon in ancient Egyptian religion
- Iah (queen), a king's mother of ancient Egypt during the 11th dynasty
- International Association of Hydrogeologists, a scientific and educational organisation
- Workers International Relief, a Berlin-based organisation whose name in German is Internationale Arbeiter-Hilfe
Iah (also Yah, Jah or Aah = " Moon") was a king's mother and queen of ancient Egypt c. 2060 BC, during the mid 11th Dynasty (2134–1991 BC). Daughter of a pharaoh, possibly Intef II, and mother of pharaoh Mentuhotep II she was the queen of Intef III.