- Megaloblast
- Megaloblastic anemia
- Megalocornea
- Megalomania
- Megamitochondria
- Megamonas
- Meganucleases
- Megarectum
- Megasphaera
- Megavitamin therapy
- Megavoltage X-rays
- Megavoltage x-rays
- Megestrol
- Megestrol acetate
- Meglitinide
- Meglumine
- Meglumine antimoniate
- Meibomian gland
- Meibomian gland dysfunction
- Meige's syndrome
- Meigs syndrome
- Meigs' syndrome
- Meiosis
- Meiotic recombination
- Meiotic spindle
- Meissner's corpuscles
- Meissner's plexus
- Melamine
- Melamine resin
- Melan A
- Melancholia
- Melancholic depression
- Melanin
- Melanin concentrating hormone
- Melanin-concentrating hormone
- Melanism
- Melanization
- Melanocortin
- Melanocortin 1 receptor
- Melanocortin 3 receptor
- Melanocortin 4 receptor
- Melanocortin receptors
- Melanocyte stimulating hormone
- Melanocytes
- Melanocytic nevi
- Melanocytic tumors
- Melanocytic tumors of uncertain malignant potential
- Melanogenesis
- Melanoma
- Melanoma-associated antigen
- Melanonychia
- Melanophilin
- Melanopsin
- Melanosis
- Melanosis coli
- Melanosome
- Melanotan ii
- Melanotic neuroectodermal tumor of infancy
- Melanotransferrin
- Melarsoprol
- Melas syndrome
- Melasma
- Melatonergic
- Melatonin
- Melatonin receptor 1B
- Melatonin receptor agonist
- Melatonin receptor agonists
- Meleagrin
- Melena
- Melibiose
- Melilotus
- Melilotus officinalis
- Melioidosis
- Melitracen
- Melittin
- Melkersson-Rosenthal syndrome
- Melnick-Needles syndrome
- Melorheostosis
- Meloxicam
- Melphalan
- Melting curve analysis
- Melting temperature
- Memantine
- Membrana granulosa
- Membrane
- Membrane attack complex
- Membrane bioreactor
- Membrane channels
- Membrane contact sites
- Membrane curvature
- Membrane depolarization
- Membrane estrogen receptor
- Membrane filter
- Membrane filtration
- Membrane fluidity
- Membrane fouling
- Membrane fusion
- Membrane fusion proteins
- Membrane glycoproteins
- Membrane lipids
- Membrane microdomains
- Membrane models
- Membrane oxygenator
- Membrane permeability
- Membrane potential
- Membrane proteins
- Membrane receptor
- Membrane ruffling
- Membrane stabilizing effect
- Membrane topology
- Membrane trafficking
- Membrane transport
- Membrane transport proteins
- Membrane-associated guanylate kinase
- Membranoproliferative glomerulonephritis
- Membranous glomerulonephritis
- Membranous labyrinth
- Membranous layer
- Membranous nephropathy
- Membranous urethra
- Memory
- Memory B cells
- Memory T cells
- Memory aid
- Memory and trauma
- Memory biases
- Memory cells
- Memory consolidation
- Memory disorders
- Memory encoding
- Memory errors
- Memory inhibition
- Memory reconsolidation
- Memory retrieval
- Memory span
- Men in nursing
- Men who have sex with men
- Men's health
- MenAfriVac
- Menadione
- Menaquinone
- Menarche
- Mendelian inheritance
- Mendelian randomization
- Meniere's disease
- Meningeal carcinomatosis
- Meningeal lymphatic vessels
- Meninges
- Meningiomas
- Meningism