- Amyoplasia, congenita 756.89
- Amyotonia 728.2
- Amyotrophia, amyotrophy, amyotrophic 728.2
- Anacidity, gastric 536.0
- Anaerosis of newborn 770.88
- Analbuminemia 273.8
- Analgesia (see also Anesthesia) 782.0
- Analphalipoproteinemia 272.5
- Anaphylactic reaction or shock (correct substance properly administered) 995.0
- Anaphylactoid reaction or shock - see Anaphylactic reaction or shock
- Anaphylaxis - see Anaphylactic reaction or shock
- Anaplasia, cervix 622.10
- Anaplasmosis, human 082.49
- Anarthria 784.51
- Anarthritic rheumatoid disease 446.5
- Anasarca 782.3
- Anaspadias 752.62
- Anastomosis
- Anatomical narrow angle (glaucoma) 365.02
- Ancylostoma (infection) (infestation) 126.9
- Ancylostomiasis (intestinal) 126.9
- Anders' disease or syndrome (adiposis tuberosa simplex) 272.8
