OIU
| Acronym | Definition |
|---|---|
| OIU | Okinawa International University (Japan) |
| OIU | Operator Interface Unit |
| OIU | Ohio Investigative Unit (Ohio Department of Public Safety) |
| OIU | Office Interface Unit |
| OIU | Optical Interface Unit |
| OIU | Osaka Imperial University (now Osaka University; Japan) |
| OIU | Optical Internal Urethrotomy |
| OIU | Orbiter Interface Unit |
| OIU | Omdurman Islamic University (Sudan) |
| OIU | Old Ignatians' Union (Lane Cove, NSW, Australia) |