| M/ Mm | Musculus/ Musculi |
| MMN | multifokal motorische Neuropathie |
| MMPI | Minnesota Multiphasic Personality Inventory |
| MMR | Masern-Mumps-Röteln |
| MMS | Monozyten-Makrophagen-System |
| MMSE | Mini-mental state examination |
| MMST | Mini-Mental State Test |
| MMV | minimale mandatory ventilation |
| MNSAR | mittlere normalisierte systolische Auswurfrate |
| MNSER | mean normalized systolic ejection rate |
| MO | Morphin |
| MOD | maturity onset diabetes (Typ II) |
| MODY | maturity onset diabetes of the young (juveniler Typ II) |
| MöF | Mitralöffnungsfläche |
| MöT | Mitralklappenöffnungston |
| MOF | multiple organ failure |
| mol | molar |
| Molgew | Molekulargewicht |
| Mon | Monat |
| MOPP | Zytostase mit Mustargen, Vincristin (Oncovin), Procarbazin, Prednison bei HL |
| MOV | Multiorganversagen |
| MP | Menopause |
| MPA | Medroxyprogesteronacetat |
| MPG | Moderate prognostic group |
| MPI | Maudsley Personality Inventory |
| MPS | myeloproliferatives Syndrom |
| MPTP | 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridin |
| MR | Magnetresonanz |
| MRCP | Magnet Resonanz Cholangio- Pankreatographie |
| MRDM | malnutrition related diabetes mellitus |