- Maternal condition, affecting fetus or newborn
- Maternity - see Delivery
- Matheiu's disease (leptospiral jaundice) 100.0
- Mauclaire's disease or osteochondrosis 732.3
- Maxcy's disease 081.0
- Maxilla, maxillary - see condition
- May (-Hegglin) anomaly or syndrome 288.2
- Mayaro fever 066.3
- Mazoplasia 610.8
- MBD (minimal brain dysfunction), child (see also Hyperkinesia) 314.9
- MCAD (medium chain acyl CoA dehydrogenase deficiency) 277.85
- McArdle (-Schmid-Pearson) disease or syndrome (glycogenosis V) 271.0
- McCune-Albright syndrome (osteitis fibrosa disseminata) 756.59
- MCLS (mucocutaneous lymph node syndrome) 446.1
- McQuarrie's syndrome (idiopathic familial hypoglycemia) 251.2
- Measles (black) (hemorrhagic) (suppressed) 055.9
- Meat poisoning - see Poisoning, food
- Meat-wrappers' asthma 506.9
- Meatitis, urethral (see also Urethritis) 597.89
- Meatus, meatal - see condition
- Meckel's
- Meconium
