- Morgagni
- Morgagni-Adams-Stokes syndrome (syncope with heart block) 426.9
- Morgagni-Stewart-Morel syndrome (hyperostosis frontalis interna) 733.3
- Moria (see also Psychosis) 298.9
- Morning sickness 643.0
- Moron 317
- Morphea (guttate) (linear) 701.0
- Morphine dependence (see also Dependence) 304.0
- Morphinism (see also Dependence) 304.0
- Morphinomania (see also Dependence) 304.0
- Morphoea 701.0
- Morquio (-Brailsford) (-Ullrich) disease or syndrome (mucopolysaccharidosis IV) 277.5
- Morris syndrome (testicular feminization) 259.51
- Morsus humanus (open wound) - see also Wound, open, by site
- Mortification (dry) (moist) (see also Gangrene) 785.4
- Morton's
- Morvan's disease 336.0
- Mosaicism, mosaic (chromosomal) 758.9
- Moschcowitz's syndrome (thrombotic thrombocytopenic purpura) 446.6
- Mother yaw 102.0
- Motion sickness (from travel, any vehicle) (from roundabouts or swings) 994.6
- Mottled teeth (enamel) (endemic) (nonendemic) 520.3
