IOL may mean:
- Iol, an ancient city in Algeria now located at Cherchell
- Imperial Oil, a large petroleum and petrochemical company
- Independent Online (South Africa), South African news and information website
- Induction of labor, also known as labor induction
- Institute of Linguists, former name of the UK Chartered Institute of Linguists
- International Linguistics Olympiad, part of the International Science Olympiad
- Intraocular lens, a clear plastic artificial lens implanted in the eye
- Ireland On-Line
- The University of New Hampshire InterOperability Laboratory (UNH-IOL), a testing facility for networking hardware