RHA
RHA is an acronym that may refer to:
- Rolled homogeneous armour
 - Regional health authority (disambiguation)
 - Regional health authority (United Kingdom), a former type of administrative organisation of the NHS in England and Wales
 - Religious Heritage of America
 - Residence hall association
 - Rice husk ash, a by-product from rice culture used as cement admixture
 - Rivers and Harbors Act, any number of various acts of legislation of the United States Congress
 - Road Haulage Association
 - Royal Hibernian Academy, and the post-nominal letters used by its members
 - Royal Horse Artillery
 - RNA helicase, an enzyme
 
Rha may refer to:
- Rha, Netherlands, a population center in Steenderen
 - Rhamnose, a monosaccharide
 - Volga River (the ancient name of the river in Latin, from Ancient Greek Ῥᾶ, thought to be a borrowing from reconstructed Scythian *Rā or *Rahā)
 - Rha (Cyrillic), a Cyrillic letter
 
Letters from alphabets that can be called rha:
- र, ड़', ढ़, र्ह — Devanagari letters which can be called ra, ṛa or rha;
 - Ԗ — the 23rd letter rha («ра») in the older (1924−1927) Moksha language Cyrillic alphabet