IOL may mean:
- Iol, an ancient city in Algeria, now Cherchell
- Independent Online, South African news website
- Institute of Linguists, UK, now Chartered Institute of Linguists
- International Linguistics Olympiad, an International Science Olympiad
- Intraocular lens, eye implant
- Ireland On-Line, a former internet service provider (ISP) in Ireland
- The University of New Hampshire InterOperability Laboratory (UNH-IOL), for networking testing
- Induction of labor, the process or treatment that stimulates childbirth