- Alveolar capillary block syndrome 516.64
- Alveolitis
- Alveolus, alveolar - see condition
- Alymphocytosis (pure) 279.2
- Alymphoplasia, thymic 279.2
- Alzheimer's
- Amastia (see also Absence, breast) 611.89
- Amaurosis (acquired) (congenital) (see also Blindness) 369.00
- Amaurotic familial idiocy (infantile) (juvenile) (late) 330.1
- Ambisexual 752.7
- Amblyopia (acquired) (congenital) (partial) 368.00
- Ameba, amebic (histolytica) - see also Amebiasis
- Amebiasis NEC 006.9
- Ameboma 006.8
- Amelia 755.4
- Ameloblastoma (M9310/0) 213.1
- Amelogenesis imperfecta 520.5
- Amenorrhea (primary) (secondary) 626.0
- Amentia (see also Disability, intellectual) 319
- American
- Ametropia (see also Disorder, accommodation) 367.9
- Amianthosis 501