IISI
| Acronym | Definition |
|---|---|
| IISI | International Iron and Steel Institute |
| IISI | Institute for Socio-Informatics (Germany) |
| IISI | Intelligent Information Systems Institute (Cornell University; est. 2000) |
| IISI | International Integrated Systems, Inc. (est. 1990; Taiwan) |
| IISI | Intermediary Insurance Services, Inc. (various locations) |
| IISI | Independent Insurance Solutions Inc. (Fort Myers, FL) |