- Andersen's glycogen storage disease 271.0
- Anderson's disease 272.7
- Andes disease 993.2
- Andrews' disease (bacterid) 686.8
- Androblastoma (M8630/1)
- Android pelvis 755.69
- Anectasis, pulmonary (newborn or fetus) 770.5
- Anemia 285.9
- Anencephalus, anencephaly 740.0
- Anergasia (see also Psychosis, organic) 294.9
- Anesthesia, anesthetic 782.0
- Anetoderma (maculosum) 701.3
- Aneuploidy NEC 758.5
- Aneurin deficiency 265.1
- Aneurysm (anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (ruptured) (saccular) (varicose) 442.9
- Angiectasis 459.89
- Angiectopia 459.9
- Angiitis 447.6
- Angina (attack) (cardiac) (chest) (effort) (heart) (pectoris) (syndrome) (vasomotor) 413.9
- Angioblastoma (M9161/1) - see Neoplasm, connective tissue, uncertain behavior
- Angiocholecystitis (see also Cholecystitis, acute) 575.0
- Angiocholitis (see also Cholecystitis, acute) 576.1
