- Marchand multiple nodular hyperplasia (liver) 571.5
- Marchesani (-Weill) syndrome (brachymorphism and ectopia lentis) 759.89
- Marchiafava (-Bignami) disease or syndrome 341.8
- Marchiafava-Micheli syndrome (paroxysmal nocturnal hemoglobinuria) 283.2
- Marcus Gunn's syndrome (jaw-winking syndrome) 742.8
- Marfan's
- Marginal
- Marie's
- Marie-Bamberger disease or syndrome (hypertrophic) (pulmonary) (secondary) 731.2
- Marie-Charcôt-Tooth neuropathic atrophy, muscle 356.1
- Marie-Strümpell arthritis or disease (ankylosing spondylitis) 720.0
- Marihuana, marijuana
- Marion's disease (bladder neck obstruction) 596.0
- Marital conflict V61.10
- Mark
- Maroteaux-Lamy syndrome (mucopolysaccharidosis VI) 277.5
- Marriage license examination V70.3
- Marrow (bone)
- Marseilles fever 082.1
- Marsh fever (see also Malaria) 084.6
- Marsh's disease (exophthalmic goiter) 242.0
- Marshall's (hidrotic) ectodermal dysplasia 757.31
