- Action, heart
- Active - see condition
- Activity decrease, functional 780.99
- Acute - see also condition
- Acyanoblepsia 368.53
- Acyanopsia 368.53
- Acystia 753.8
- Acystinervia - see Neurogenic, bladder
- Acystineuria - see Neurogenic, bladder
- Adactylia, adactyly (congenital) 755.4
- Adair-Dighton syndrome (brittle bones and blue sclera, deafness) 756.51
- Adamantinoblastoma (M9310/0) - see Ameloblastoma
- Adamantinoma (M9310/0) - see Ameloblastoma
- Adamantoblastoma (M9310/0) - see Ameloblastoma
- Adams-Stokes (-Morgagni) disease or syndrome (syncope with heart block) 426.9
- Adaptation reaction (see also Reaction, adjustment) 309.9
- Addiction - see also Dependence
- Addison's
- Addison-Biermer anemia (pernicious) 281.0
- Addison-Gull disease - see Xanthoma
- Addisonian crisis or melanosis (acute adrenocortical insufficiency) 255.4
- Additional - see also Accessory
