- Brachymorphism and ectopia lentis 759.89
- Bradley's disease (epidemic vomiting) 078.82
- Bradycardia 427.89
- Bradykinesia 781.0
- Bradypnea 786.09
- Brailsford's disease 732.3
- Brailsford-Morquio disease or syndrome (mucopolysaccharidosis IV) 277.5
- Brain - see also condition
- Branched-chain amino-acid disease 270.3
- Branchial - see condition
- Brandt's syndrome (acrodermatitis enteropathica) 686.8
- Brash (water) 787.1
- Brass-founders' ague 985.8
- Bravais-Jacksonian epilepsy (see also Epilepsy) 345.5
- Braxton Hicks contractions 644.1
- Braziers' disease 985.8
- Brazilian
- BRBPR (bright red blood per rectum) 569.3
- Break
- Breakbone fever 061
- Breakdown
- Breast - see also condition