- Agranulocytosis (angina) (chronic) (cyclical) (genetic) (infantile) (periodic) (pernicious) 288.0
- Agraphia (absolute) 784.69
- Agrypnia (see also Insomnia) 780.52
- Ague (see also Malaria) 084.6
- Agyria 742.2
- Ahumada-del Castillo syndrome (nonpuerperal galactorrhea and amenorrhea) 253.1
- AIDS 042
- AIDS virus (disease) (illness) 042
- AIDS-associated retrovirus (disease) (illness) 042
- AIDS-associated virus (disease) (illness) 042
- AIDS-like disease (illness) (syndrome) 042
- AIDS-related complex 042
- AIDS-related conditions 042
- AIDS-related virus (disease) (illness) 042
- Ailment, heart - see Disease, heart
- Ailurophobia 300.29
- Ainhum (disease) 136.0
- Air
- Airplane sickness 994.6
- Akathisia, acathisia 781.0
- Akinesia algeria 352.6
- Akiyami 100.89
