- Jaccoud\’s syndrome
- Jackson\’s
- Jacquet\’s dermatitis (diaper dermatitis), L22
- Jadassohn-Pellizari\’s disease or anetoderma, L90.2
- Jadassohn\’s
- Jaffe-Lichtenstein syndrome (-Uehlinger)
- Jakob-Creutzfeldt disease or syndrome
- Jaksch-Luzet disease, D64.89
- Jamaican
- Janet\’s disease, F48.8
- Janiceps, Q89.4
- Jansky-Bielschowsky amaurotic idiocy, E75.4
- Japanese
- Jaundice (yellow), R17
- Jaw
- Jaw-winking phenomenon or syndrome, Q07.8
- Jüngling\’s disease
- Jealousy
- Jejunitis
- Jejunostomy status, Z93.4
- Jejunum, jejunal
- Jensen\’s disease
- Jerks, myoclonic, G25.3
- Jervell-Lange-Nielsen syndrome, I45.81
- Jeune\’s disease, Q77.2
- Jigger disease, B88.1
- Job\’s syndrome (chronic granulomatous disease), D71
- Joint
- Jordan\’s anomaly or syndrome, D72.0
- Joseph-Diamond-Blackfan anemia (congenital hypoplastic), D61.01
- Jungle yellow fever, A95.0
- Juvenile