| MALDI | Matrix-assisted Laser Desorption Ionization | - | Medical |
| MB | Megabase | - | Medical |
| MBC | Massachusetts Biotechnology Council | - | Medical |
| MBL | Marine Biological Laboratory | - | Medical |
| MCD | Mouse Cytogenetic Database | - | Medical |
| MDA | Muscular Dystrophy Assoc. | - | Medical |
| MEMS | Microelectromechanical Systems | - | Medical |
| MGC | Mouse Genome Conference | - | Medical |
| MGD | Mouse Genome Database | - | Medical |
| MGI | Microbial Genome Initiative | - | Medical |
| MHC | Major Histocompatibility Complex | - | Medical |
| MIMBD | Meet. On The Interconnection Of Mol. Biol. Databases | - | Medical |
| MIT | Massachusetts Institute Of Technology | - | Medical |
| MMRF | Marshfield Medical Research Foundation | - | Medical |
| MNBWS | Miami Nature Biotechnology Winter Symposium | - | Medical |
| MOD | March Of Dimes | - | Medical |
| MOU | Memorandum Of Understanding | - | Medical |
| MRC | Medical Research Council | - | Medical |
| MS | Mass Spectrometry | - | Medical |
