| Abbreviation | Definition |
|---|---|
| MRCOA | Medical Research Council trial in Older Adults |
| MRCOG | Member, Royal College of Obstetricians and Gynaecologists |
| MRCOphth | Member, Royal College of Ophthalmologists |
| MRCP(I)XX | Member, Royal College of Physicians of Ireland |
| MRCP(XYZ)XX | Member of the Royal College of Physicians of (Edinburgh), (Glasgow) or (London) |
| MRCPath | Member, Royal College of Pathologists |
| MRCPCH | Member, Royal College of Paediatrics and Child Health |
| MRCPS | Member, Royal College of Physicians and Surgeons |
| MRCPsych | Member, Royal College of Psychiatrists |
| MRCR | Member, Royal College of Radiologists |
| MRCS | Member, Royal College of Surgeons |
| MREC | mismatch repair enzyme cleavage |
| MREC | Multicentre Research Ethics Committee (ethics committee) |
| MRHA | Medicines and Healthcare Products Regulatory Authority |
| MRO | Medical Records Officer |
| MRPharmS | Member of the Royal Pharmaceutical Society of Great Britain |
| MRSAXX | Meticillin-resistant Staphylococcus aureus |
| MRT | Metabolic response testing |
| MS | Maffuci syndrome |
| MS | magnesium sulphate |