MIIS is an acronym that could refer to a number of things.
- Monterey Institute of International Studies, a graduate school of Middlebury College in California
- MIIS (football club), a soccer team in the MPSL, featuring students, faculty, and staff from the Monterey Institute of International Studies
- MIIS (programming language), a computer programming language
- Microsoft Identity Integration Server, Microsoft server software for identity and access management solutions
- Mii, a simulated avatar created on the Wii console