FRU can refer to:
- Fiji Rugby Union
- Federal Reserve Unit, the mobile riot police of the Royal Malaysian Police
- Field Replaceable Unit, a circuit board or part that can be quickly and easily removed and replaced by the user or by a technician without having to send the entire product or system to a repair facility.
- Fleet Radio Unit, USN cryptographic unit in World War II
- Force Research Unit, the name given to a British military intelligence unit in Northern Ireland
- Manas International Airport, in Bishkek, Kyrgyzstan, whose IATA code is FRU.
- Free Representation Unit, a British legal charity providing pro bono representation, particularly in the areas of employment and social security.