| Abbreviation | Definition |
|---|---|
| MPRI | Midwest Proton Radiotherapy Institute |
| MPS | Max Planck Institute for Solar System Research |
| MPSI | Merrill Palmer Skillman Institute |
| MPSI | Michigan Public Service Institute |
| MPSI | Minnesota Psychoanalytic Society and Institute |
| MPTI | Moscow Physical Technical Institute |
| MPTI | Multicultural Psychotherapy Training Institute |
| MRI | Mathematical Research Institute |
| MRI | Medical Research Institute |
| MRI | Mental Research Institute |
| MRI | Monetary Research Institute |
| MRIN | Mochtar Riady Institute for Nanotechnology |
| MRINA | Member of the Royal Institute of Naval Architects |
| MRTI | Materials Research and Technology Institute |
| MRTI | Myanmar Responsible Tourism Institute |
| MSAI | Main Street America Institute |
| MSAI | Mississippi Summer Art Institute |
| MSCI | Metal Service Center Institute |
| MSDI | Missouri State Debate Institute |
| MSEI | Melbourne Social Equity Institute |