- MEN1
- MEOX2
- MERCI Retriever
- MERRF syndrome
- MERS
- MERTK
- MESP2
- METAP2
- METLIN
- MF59
- MG132
- MHC
- MHC class I
- MHC class II
- MHC class III
- MHC restriction
- MHealth
- MIA PaCa-2
- MIBE
- MIBG
- MIDCAB
- MIMIC
- MIND diet
- MITF
- MIXL1
- MK-2206
- MK-434
- MLL
- MLL2
- MLL3
- MLL4
- MMEJ
- MMP1
- MMP11
- MMP14
- MMP15
- MMP19
- MMP2
- MMP20
- MMP24
- MMP27
- MMP3
- MMP7
- MMP8
- MMP9
- MMPI
- MMR vaccine
- MNDA
- MNGIE syndrome
- MNT
- MNX1
- MODELLER
- MODY 1
- MODY 2
- MOG antibody disease
- MOMS Trial
- MOPP
- MOPS
- MPC1
- MPI
- MPJE
- MPP+
- MPSS
- MPV
- MR enterography
- MRC
- MRC-5
- MRGPRX2
- MRI
- MRI sequence
- MRM
- MRN complex
- MRSA
- MRSE
- MS Contin
- MS4A2
- MSA
- MSCEIT
- MSCRAMM
- MSH
- MSH6
- MSR1
- MST
- MSX1
- MT-45
- MT-ATP6
- MT-CYB
- MT-ND5
- MT-RNR1
- MTA
- MTA1
- MTA2
- MTBE
- MTBVAC
- MTHFR deficiency
- MTORC1
- MTORC2
- MTS assay
- MTT assay
- MTTF
- MUC1
- MUNE
- MURCS association
- MUTYH-associated polyposis
- MVA85A
- MVTR
- MXenes
- MYB
- MYBL2
- MYC
- MYCL
- MYCN
- MYD88
- MYF5
- MYF6
- MYH7
- MYL2
- MYO7A
- MYOT
- MYT1
- Maalox
- MacConkey agar
- Maceration
- Machado-Joseph disease
- Machine ethics
- Machine learning
- Machine perfusion
- Macitentan
- Maclura pomifera
- Macro domain
- Macroadenoma
- Macroalbuminuria
- Macroautophagy
- Macrobiotic diet
- Macrocephalus
- Macrocephaly
- Macrocyclic compounds
- Macrocytic anemia
- Macrocytosis
- Macrodontia
- Macroglia
- Macroglobulin
- Macroglobulinemia
- Macroglossia
- Macrolide antibiotics
- Macrolides
- Macromolecular assembly
- Macromolecular crowding
- Macromolecules
- Macromonomers