The abbreviation IOR may refer to:
- Institute of Recruiters, a non-profit Institute for recruiters and HR professionals
- Index of refraction
- Istituto per le Opere di Religione (Institute for Religious Works), the "Vatican Bank"
- Interoperable Object Reference, a reference to a CORBA or RMI-IIOP object
- Inhibition of return, a phenomenon in visual perception
- International Offshore Rule, an early handicapping system for yacht racing
- Interleaved or Random, a computer benchmark for I/O
- Independent Order of Rechabites
- inclusive or - as opposed to XOR (exclusive OR)
- IORgroup Ltd (formerly Interiors of Richmond), a London-based commercial interior design company
- I.O.R., optics company of Romania
- Interest on Reserves, a term used in macroeconomics having to do with reserves placed at the central bank
- India Office Records
- Indian Ocean Region
- Indian Ocean Rim.