| Abbreviation | Definition |
|---|---|
| MRAA | Medical Research Agencies of America |
| MRC | Marmara Research Center |
| MRC | Medical Research Charities |
| MRC | Medical Research Council |
| MRC | Membership Renewal Credit |
| MRC | Ye Ed suggests capitals: Marmara Research Center |
| MRCA | Medical Research Charities of America |
| MRCS | Malaysian Red Crescent Society |
| MRF | Melanoma Research Foundation |
| MRF | Motorcycle Riders Foundation |
| MRIC | Maumee RAP Implementation Committee |
| MRM | Member Relationship Management |
| MRM | Miami Rescue Mission |
| MROC | Millennium Report Oversight Committee |
| MROO | Municipal Retirees Organization Ontario |
| MRPI | Metropolitan Research and Policy Institute |
| MRPS | Madiga Reservation Porata Samiti |
| MRQ | Mouvement républicain du Québec (Republican Movement of Quebec) |
| MRR | Michigan Rabbit Rescue |
| MRRL | Michigan Rabbit Rescue League |