- Bostock's catarrh (see also Fever, hay) 477.9
- Boston exanthem 048
- Botalli, ductus (patent) (persistent) 747.0
- Bothriocephalus latus infestation 123.4
- Botulism 005.1
- Bouba (see also Yaws) 102.9
- Bouffée délirante 298.3
- Bouillaud's disease or syndrome (rheumatic heart disease) 391.9
- Bourneville's disease (tuberous sclerosis) 759.5
- Boutonneuse fever 082.1
- Boutonniere
- Bouveret (-Hoffmann) disease or syndrome (paroxysmal tachycardia) 427.2
- Bovine heart - see Hypertrophy, cardiac
- Bowel - see condition
- Bowen's
- Bowing
- Bowleg(s) 736.42
- Boyd's dysentery 004.2
- Brachial - see condition
- Brachman-de Lange syndrome (Amsterdam dwarf, intellectual disabilities, and brachycephaly) 759.89
- Brachycardia 427.89
- Brachycephaly 756.0
